Data Cleaning & Manipulation

Monday, April 13

Today we will…

• Comments from Week 2
• New Material
  • Data wrangling
  • Introduce the dplyr package.
  • Use dplyr verbs to manipulate data.
• PA 3: Identify the Mystery College

Follow along

Remember to download, save, and open up the handout for today!

Questions from Week 2?

Stat departmnet joke of the week by Syliva Du Spring 2026. Image created with AI.

Style Note of the Day - Spacing

• Always put a space after a comma, but never before
• Surround = with spaces when naming arguments
• Surround many mathematical operators (+, -, *) with spaces (but not all!)
• Don’t include spaces around parentheses for function calls (although you may include a new-line)

Style Note of the Day - Spacing

Nice:

mean(x, na.rm = TRUE)

height <- (feet * 12) + inches

2^2

No thank you:

mean(x,na.rm=TRUE)
mean( x , na.rm = TRUE )
mean (x, na.rm = TRUE)

height<-(feet*12)+inches

2 ^ 2

Data Wrangling with dplyr

(Allison Horst)

Demonstration Data – Cereal

library(liver)
data(cereal)

. . .

Data Structure

str(cereal, give.attr = FALSE)

'data.frame':   77 obs. of  16 variables:
 $ name    : Factor w/ 77 levels "100% Bran","100% Natural Bran",..: 1 2 3 4 5 6 7 8 9 10 ...
 $ manuf   : Factor w/ 7 levels "A","G","K","N",..: 4 6 3 3 7 2 3 2 7 5 ...
 $ type    : Factor w/ 2 levels "cold","hot": 1 1 1 1 1 1 1 1 1 1 ...
 $ calories: int  70 120 70 50 110 110 110 130 90 90 ...
 $ protein : int  4 3 4 4 2 2 2 3 2 3 ...
 $ fat     : int  1 5 1 0 2 2 0 2 1 0 ...
 $ sodium  : int  130 15 260 140 200 180 125 210 200 210 ...
 $ fiber   : num  10 2 9 14 1 1.5 1 2 4 5 ...
 $ carbo   : num  5 8 7 8 14 10.5 11 18 15 13 ...
 $ sugars  : int  6 8 5 0 8 10 14 8 6 5 ...
 $ potass  : int  280 135 320 330 -1 70 30 100 125 190 ...
 $ vitamins: int  25 0 25 25 25 25 25 25 25 25 ...
 $ shelf   : int  3 3 3 3 3 1 2 3 1 3 ...
 $ weight  : num  1 1 1 1 1 1 1 1.33 1 1 ...
 $ cups    : num  0.33 1 0.33 0.5 0.75 0.75 1 0.75 0.67 0.67 ...
 $ rating  : num  68.4 34 59.4 93.7 34.4 ...

Head of the Data

head(cereal) 

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1	0.33	68.40297
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1	1.00	33.98368
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1	0.33	59.42551
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1	0.50	93.70491
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1	0.75	34.38484
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1	0.75	29.50954

Data Summary

summary(cereal)

                        name    manuf    type       calories    
 100% Bran                : 1   A: 1   cold:74   Min.   : 50.0  
 100% Natural Bran        : 1   G:22   hot : 3   1st Qu.:100.0  
 All-Bran                 : 1   K:23             Median :110.0  
 All-Bran with Extra Fiber: 1   N: 6             Mean   :106.9  
 Almond Delight           : 1   P: 9             3rd Qu.:110.0  
 Apple Cinnamon Cheerios  : 1   Q: 8             Max.   :160.0  
 (Other)                  :71   R: 8                            
    protein           fat            sodium          fiber       
 Min.   :1.000   Min.   :0.000   Min.   :  0.0   Min.   : 0.000  
 1st Qu.:2.000   1st Qu.:0.000   1st Qu.:130.0   1st Qu.: 1.000  
 Median :3.000   Median :1.000   Median :180.0   Median : 2.000  
 Mean   :2.545   Mean   :1.013   Mean   :159.7   Mean   : 2.152  
 3rd Qu.:3.000   3rd Qu.:2.000   3rd Qu.:210.0   3rd Qu.: 3.000  
 Max.   :6.000   Max.   :5.000   Max.   :320.0   Max.   :14.000  
                                                                 
     carbo          sugars           potass          vitamins     
 Min.   :-1.0   Min.   :-1.000   Min.   : -1.00   Min.   :  0.00  
 1st Qu.:12.0   1st Qu.: 3.000   1st Qu.: 40.00   1st Qu.: 25.00  
 Median :14.0   Median : 7.000   Median : 90.00   Median : 25.00  
 Mean   :14.6   Mean   : 6.922   Mean   : 96.08   Mean   : 28.25  
 3rd Qu.:17.0   3rd Qu.:11.000   3rd Qu.:120.00   3rd Qu.: 25.00  
 Max.   :23.0   Max.   :15.000   Max.   :330.00   Max.   :100.00  
                                                                  
     shelf           weight          cups           rating     
 Min.   :1.000   Min.   :0.50   Min.   :0.250   Min.   :18.04  
 1st Qu.:1.000   1st Qu.:1.00   1st Qu.:0.670   1st Qu.:33.17  
 Median :2.000   Median :1.00   Median :0.750   Median :40.40  
 Mean   :2.208   Mean   :1.03   Mean   :0.821   Mean   :42.67  
 3rd Qu.:3.000   3rd Qu.:1.00   3rd Qu.:1.000   3rd Qu.:50.83  
 Max.   :3.000   Max.   :1.50   Max.   :1.500   Max.   :93.70  
                                                               

Before jumping in to code…

In groups, sketch the output and describe in words steps you would take from cereal data to get the output for each of the following:

1. What is the ratio of fiber to sugars in each cereal?

2. Create a new dataset that only has Nabisco cereals and displays the protein, fat, and sodium in each.

3. Create a table that shows, for each manufacturer the average and standard deviation of the grams of sugar in their cereals, along with how many cereals are in the data for each manufacturer. Order the table from most sugar (on average) to least.

dplyr

dplyr is part of the tidyverse that provides us with the Grammar of Data Manipulation.

• This package gives us the tools to wrangle, manipulate, and tidy our data with ease.
• Check out the dplyr cheatsheet.

dplyr verbs

• filter() – select rows based on their values
• arrange() – sort rows based on their values
• select() – select columns
• mutate() – add new columns by transforming other columns
• summarize() – perform summary operations on columns
• group_by() – facilitate group-wise operations

. . .

Use the pipe operator (|> or %>%) to chain together data wrangling operations.

Match the dplyr verb

In groups match the dplyr verbs to your suggested steps:

1. What is the ratio of fiber to sugars in each cereal?

2. Create a new dataset that only has Nabisco cereals and displays the protein, fat, and sodium in each.

3. Create a table that shows, for each manufacturer the average and standard deviation of the grams of sugar in their cereals, along with how many cereals are in the data for each manufacturer. Order the table from most sugar (on average) to least.

The Pipe Operator

No matter how complex and polished the individual operations are, it is often the quality of the glue that most directly determines the power of the system.

— Hal Abelson

The Pipe Operator

• The pipe specifies a sequence of operations.
• The output from one operation is passed (piped) into the first argument of the next operation.

. . .

These are equivalent:

summary(cereal)

cereal |> 
  summary()

The Pipe Operator

• The “original” pipe: %>%

  • Loaded with tidyverse package (part of magrittr).

• The “native” pipe: |>

  • Created in R version 4.1.0.
  • Tools > Global Options... > Code > check Use native pipe operator box to use keyboard shortcut:
    • ctrl/cmd + shift + m

The Pipe Operator

• With dplyr, your code should read like a sentence.

• The data is the primary object in your sentence, so it should come first in your code.

• The pipe operator is an important part of that readability.

. . .

dr_c |>
  bake_a_dessert()

. . .

dr_c |>
  put_on("apron") |>
  bake_a_dessert(type = "cake")

. . .

SO MUCH better than:

  bake_a_dessert(put_on(dr_c, "apron"), type = "cake")

Data Comes First!

dplyr verbs are designed for piping!

• filter(.data = cereal, ...)
• select(.data = cereal, ...)
• mutate(.data = cereal, ...)

. . .

The pipe operator is your friend!

filter()

knitr::include_graphics("https://github.com/allisonhorst/stats-illustrations/raw/main/rstats-artwork/dplyr_filter.jpg")

(Allison Horst)

filter()

We filter to the rows (observations) we would like to keep in the data.

. . .

cereal |> 
  filter(sugars < 5)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8	0	330	25	3	1.00	0.50	93.70491
Cheerios	G	cold	110	6	2	290	2.0	17	1	105	25	1	1.00	1.25	50.76500
Corn Chex	R	cold	110	2	0	280	0.0	22	3	25	25	1	1.00	1.00	41.44502
Corn Flakes	K	cold	100	2	0	290	1.0	21	2	35	25	1	1.00	1.00	45.86332
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21	0	-1	0	2	1.00	1.00	64.53382
Crispix	K	cold	110	2	0	220	1.0	21	3	30	25	3	1.00	1.00	46.89564
Grape-Nuts	P	cold	110	3	0	170	3.0	17	3	90	25	3	1.00	0.25	53.37101
Great Grains Pecan	P	cold	120	3	3	75	3.0	13	4	100	25	3	1.00	0.33	45.81172
Kix	G	cold	110	2	1	260	0.0	21	3	40	25	2	1.00	1.50	39.24111
Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1.00	1.00	54.85092
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18	2	90	25	3	1.00	1.00	59.64284
Product 19	K	cold	100	3	0	320	1.0	20	3	45	100	3	1.00	1.00	41.50354
Puffed Rice	Q	cold	50	1	0	0	0.0	13	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10	0	50	0	3	0.50	1.00	63.00565
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1.00	0.67	50.82839
Rice Chex	R	cold	110	1	0	240	0.0	23	2	30	25	1	1.00	1.13	41.99893
Rice Krispies	K	cold	110	2	0	290	0.0	22	3	35	25	1	1.00	1.00	40.56016
Shredded Wheat	N	cold	80	2	0	0	3.0	16	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20	0	120	0	1	1.00	0.67	72.80179
Special K	K	cold	110	6	0	230	1.0	16	3	55	25	1	1.00	1.00	53.13132
Total Corn Flakes	G	cold	110	2	1	200	0.0	21	3	35	100	3	1.00	1.00	38.83975
Total Whole Grain	G	cold	100	3	1	200	3.0	16	3	110	100	3	1.00	1.00	46.65884
Triples	G	cold	110	2	1	250	0.0	21	3	60	25	3	1.00	0.75	39.10617
Wheat Chex	R	cold	100	3	1	230	3.0	17	3	115	25	1	1.00	0.67	49.78744
Wheaties	G	cold	100	3	1	200	3.0	17	3	110	25	1	1.00	1.00	51.59219

filter()

We can add multiple filters to our data, to get a more specific subset.

cereal |> 
  filter(sugars < 5,
         type == "hot")

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21	0	-1	0	2	1	1.00	64.53382
Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1	1.00	54.85092
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1	0.67	50.82839

filter(): Handy Helpers!

• > – greater than
• < – less than
• == – equal to
• ! – not
• %in% – checks if an element belongs to a vector
• is.na() – binary evaluation of missing values

. . .

• & and , – and
• | – or

filter(): |

cereal |> 
  filter(sugars < 5,
         type == "hot")

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21	0	-1	0	2	1	1.00	64.53382
Maypo	A	hot	100	4	1	0	0.0	16	3	95	25	2	1	1.00	54.85092
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1	-1	110	0	1	1	0.67	50.82839

. . .

What if I wanted either non-sugary cereals or hot cereals…

cereal |> 
  filter(sugars < 5 |
           type == "hot")

filter(): %in%

Are you interested in observations with values in multiple levels?

. . .

cereal |> 
  filter(name %in% c("Cheerios", "Cinnamon Toast Crunch", "Raisin Bran", "Cracklin' Oat Bran"))

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Cheerios	G	cold	110	6	2	290	2	17	1	105	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	G	cold	120	1	3	210	0	13	9	45	25	2	1.00	0.75	19.82357
Cracklin' Oat Bran	K	cold	110	3	3	140	4	10	7	160	25	3	1.00	0.50	40.44877
Raisin Bran	K	cold	120	3	1	210	5	14	12	240	25	2	1.33	0.75	39.25920

filter(): Related Functions

These functions select rows by row number.

• slice() – select rows with the specified indicies
• slice_head() – select the first n rows
• slice_tail() – select the last n rows
• slice_sample() – randomly select n rows

A new function that removes rows instead of keeping:

• filter_out() – remove rows based on criteria

arrange()

arrange()

We arrange the rows of the data in order of a particular variable.

. . .

cereal |> 
  arrange(sodium)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354

arrange()

We can arrange by multiple variables.

. . .

cereal |> 
  arrange(sodium, sugars) |>
  select(name:type, sodium, sugars)

name	manuf	type	sodium	sugars
Quaker Oatmeal	Q	hot	0	-1
Puffed Rice	Q	cold	0	0
Puffed Wheat	Q	cold	0	0
Shredded Wheat	N	cold	0	0
Shredded Wheat 'n'Bran	N	cold	0	0
Shredded Wheat spoon size	N	cold	0	0
Maypo	A	hot	0	3
Raisin Squares	K	cold	0	6
Frosted Mini-Wheats	K	cold	0	7
Strawberry Fruit Wheats	N	cold	15	5
100% Natural Bran	Q	cold	15	8
Golden Crisp	P	cold	45	15
Smacks	K	cold	70	15
Great Grains Pecan	P	cold	75	4
Cream of Wheat (Quick)	N	hot	80	0
Corn Pops	K	cold	90	12
Muesli Raisins; Dates; & Almonds	R	cold	95	11
Froot Loops	K	cold	125	13
Apple Jacks	K	cold	125	14
100% Bran	N	cold	130	6
Quaker Oat Squares	Q	cold	135	6
Fruity Pebbles	P	cold	135	12
All-Bran with Extra Fiber	K	cold	140	0
Grape Nuts Flakes	P	cold	140	5
Clusters	G	cold	140	7
Cracklin' Oat Bran	K	cold	140	7
Raisin Nut Bran	G	cold	140	8
Crispy Wheat & Raisins	G	cold	140	10
Trix	G	cold	140	12
Life	Q	cold	150	6
Muesli Raisins; Peaches; & Pecans	R	cold	150	11
Mueslix Crispy Blend	K	cold	150	13
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	160	10
Nutri-grain Wheat	K	cold	170	2
Grape-Nuts	P	cold	170	3
Just Right Crunchy Nuggets	K	cold	170	6
Just Right Fruit & Nut	K	cold	170	9
Oatmeal Raisin Crisp	G	cold	170	10
Apple Cinnamon Cheerios	G	cold	180	10
Honey-comb	P	cold	180	11
Lucky Charms	G	cold	180	12
Cocoa Puffs	G	cold	180	13
Count Chocula	G	cold	180	13
Double Chex	R	cold	190	5
Nut&Honey Crunch	K	cold	190	9
Total Raisin Bran	G	cold	190	14
Total Corn Flakes	G	cold	200	3
Total Whole Grain	G	cold	200	3
Wheaties	G	cold	200	3
Bran Chex	R	cold	200	6
Almond Delight	R	cold	200	8
Wheaties Honey Gold	G	cold	200	8
Frosted Flakes	K	cold	200	11
Post Nat. Raisin Bran	P	cold	200	14
Bran Flakes	P	cold	210	5
Basic 4	G	cold	210	8
Cinnamon Toast Crunch	G	cold	210	9
Raisin Bran	K	cold	210	12
Crispix	K	cold	220	3
Multi-Grain Cheerios	G	cold	220	6
Nutri-Grain Almond-Raisin	K	cold	220	7
Honey Graham Ohs	Q	cold	220	11
Cap'n'Crunch	Q	cold	220	12
Special K	K	cold	230	3
Wheat Chex	R	cold	230	3
Rice Chex	R	cold	240	2
Fruitful Bran	K	cold	240	12
Triples	G	cold	250	3
Honey Nut Cheerios	G	cold	250	10
Kix	G	cold	260	3
All-Bran	K	cold	260	5
Corn Chex	R	cold	280	3
Golden Grahams	G	cold	280	9
Cheerios	G	cold	290	1
Corn Flakes	K	cold	290	2
Rice Krispies	K	cold	290	3
Product 19	K	cold	320	3

arrange(): Descending Order

Default is ascending order…

cereal |> 
  arrange(sodium)

…but can add desc() to get descending order!

cereal |> 
  arrange(desc(sodium))

arrange(): Related Functions

These functions implicitly arrange the data before slicing it (selecting rows).

• slice_min() – select rows with the lowest value(s) of a variable
• slice_max() – select rows with the highest value(s) of a variable

slice_max()

Selects the n rows with the maximum values of the specified variable.

cereal |> 
  slice_max(order_by = sugars, n = 3)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Golden Crisp	P	cold	100	2	0	45	0	11	15	40	25	1	1.00	0.88	35.25244
Smacks	K	cold	110	2	1	70	1	9	15	40	25	2	1.00	0.75	31.23005
Apple Jacks	K	cold	110	2	0	125	1	11	14	30	25	2	1.00	1.00	33.17409
Post Nat. Raisin Bran	P	cold	120	3	1	200	6	11	14	260	25	3	1.33	0.67	37.84059
Total Raisin Bran	G	cold	140	3	1	190	4	15	14	230	100	3	1.50	1.00	28.59278

. . .

cereal |> 
  slice_max(order_by = sugars, n = 3, with_ties = FALSE)

Efficiency note

Use slice_max()/slice_min():

cereal |> 
  slice_max(order_by = sugars, n = 3)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Golden Crisp	P	cold	100	2	0	45	0	11	15	40	25	1	1.00	0.88	35.25244
Smacks	K	cold	110	2	1	70	1	9	15	40	25	2	1.00	0.75	31.23005
Apple Jacks	K	cold	110	2	0	125	1	11	14	30	25	2	1.00	1.00	33.17409
Post Nat. Raisin Bran	P	cold	120	3	1	200	6	11	14	260	25	3	1.33	0.67	37.84059
Total Raisin Bran	G	cold	140	3	1	190	4	15	14	230	100	3	1.50	1.00	28.59278

Not arrange() and slice_head():

cereal |> 
  arrange(desc(sugars)) |> 
  slice_head(n = 3)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
Golden Crisp	P	cold	100	2	0	45	0	11	15	40	25	1	1	0.88	35.25244
Smacks	K	cold	110	2	1	70	1	9	15	40	25	2	1	0.75	31.23005
Apple Jacks	K	cold	110	2	0	125	1	11	14	30	25	2	1	1.00	33.17409

select()

select()

We select which variables we would like to remain in the data.

. . .

cereal |> 
  select(name, manuf, calories, cups)

name	manuf	calories	cups
100% Bran	N	70	0.33
100% Natural Bran	Q	120	1.00
All-Bran	K	70	0.33
All-Bran with Extra Fiber	K	50	0.50
Almond Delight	R	110	0.75
Apple Cinnamon Cheerios	G	110	0.75
Apple Jacks	K	110	1.00
Basic 4	G	130	0.75
Bran Chex	R	90	0.67
Bran Flakes	P	90	0.67
Cap'n'Crunch	Q	120	0.75
Cheerios	G	110	1.25
Cinnamon Toast Crunch	G	120	0.75
Clusters	G	110	0.50
Cocoa Puffs	G	110	1.00
Corn Chex	R	110	1.00
Corn Flakes	K	100	1.00
Corn Pops	K	110	1.00
Count Chocula	G	110	1.00
Cracklin' Oat Bran	K	110	0.50
Cream of Wheat (Quick)	N	100	1.00
Crispix	K	110	1.00
Crispy Wheat & Raisins	G	100	0.75
Double Chex	R	100	0.75
Froot Loops	K	110	1.00
Frosted Flakes	K	110	0.75
Frosted Mini-Wheats	K	100	0.80
Fruit & Fibre Dates; Walnuts; and Oats	P	120	0.67
Fruitful Bran	K	120	0.67
Fruity Pebbles	P	110	0.75
Golden Crisp	P	100	0.88
Golden Grahams	G	110	0.75
Grape Nuts Flakes	P	100	0.88
Grape-Nuts	P	110	0.25
Great Grains Pecan	P	120	0.33
Honey Graham Ohs	Q	120	1.00
Honey Nut Cheerios	G	110	0.75
Honey-comb	P	110	1.33
Just Right Crunchy Nuggets	K	110	1.00
Just Right Fruit & Nut	K	140	0.75
Kix	G	110	1.50
Life	Q	100	0.67
Lucky Charms	G	110	1.00
Maypo	A	100	1.00
Muesli Raisins; Dates; & Almonds	R	150	1.00
Muesli Raisins; Peaches; & Pecans	R	150	1.00
Mueslix Crispy Blend	K	160	0.67
Multi-Grain Cheerios	G	100	1.00
Nut&Honey Crunch	K	120	0.67
Nutri-Grain Almond-Raisin	K	140	0.67
Nutri-grain Wheat	K	90	1.00
Oatmeal Raisin Crisp	G	130	0.50
Post Nat. Raisin Bran	P	120	0.67
Product 19	K	100	1.00
Puffed Rice	Q	50	1.00
Puffed Wheat	Q	50	1.00
Quaker Oat Squares	Q	100	0.50
Quaker Oatmeal	Q	100	0.67
Raisin Bran	K	120	0.75
Raisin Nut Bran	G	100	0.50
Raisin Squares	K	90	0.50
Rice Chex	R	110	1.13
Rice Krispies	K	110	1.00
Shredded Wheat	N	80	1.00
Shredded Wheat 'n'Bran	N	90	0.67
Shredded Wheat spoon size	N	90	0.67
Smacks	K	110	0.75
Special K	K	110	1.00
Strawberry Fruit Wheats	N	90	1.00
Total Corn Flakes	G	110	1.00
Total Raisin Bran	G	140	1.00
Total Whole Grain	G	100	1.00
Triples	G	110	0.75
Trix	G	110	1.00
Wheat Chex	R	100	0.67
Wheaties	G	100	1.00
Wheaties Honey Gold	G	110	0.75

select()

You can use : to select a sequence of columns.

cereal |> 
  select(name:calories)

name	manuf	type	calories
100% Bran	N	cold	70
100% Natural Bran	Q	cold	120
All-Bran	K	cold	70
All-Bran with Extra Fiber	K	cold	50
Almond Delight	R	cold	110
Apple Cinnamon Cheerios	G	cold	110
Apple Jacks	K	cold	110
Basic 4	G	cold	130
Bran Chex	R	cold	90
Bran Flakes	P	cold	90
Cap'n'Crunch	Q	cold	120
Cheerios	G	cold	110
Cinnamon Toast Crunch	G	cold	120
Clusters	G	cold	110
Cocoa Puffs	G	cold	110
Corn Chex	R	cold	110
Corn Flakes	K	cold	100
Corn Pops	K	cold	110
Count Chocula	G	cold	110
Cracklin' Oat Bran	K	cold	110
Cream of Wheat (Quick)	N	hot	100
Crispix	K	cold	110
Crispy Wheat & Raisins	G	cold	100
Double Chex	R	cold	100
Froot Loops	K	cold	110
Frosted Flakes	K	cold	110
Frosted Mini-Wheats	K	cold	100
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120
Fruitful Bran	K	cold	120
Fruity Pebbles	P	cold	110
Golden Crisp	P	cold	100
Golden Grahams	G	cold	110
Grape Nuts Flakes	P	cold	100
Grape-Nuts	P	cold	110
Great Grains Pecan	P	cold	120
Honey Graham Ohs	Q	cold	120
Honey Nut Cheerios	G	cold	110
Honey-comb	P	cold	110
Just Right Crunchy Nuggets	K	cold	110
Just Right Fruit & Nut	K	cold	140
Kix	G	cold	110
Life	Q	cold	100
Lucky Charms	G	cold	110
Maypo	A	hot	100
Muesli Raisins; Dates; & Almonds	R	cold	150
Muesli Raisins; Peaches; & Pecans	R	cold	150
Mueslix Crispy Blend	K	cold	160
Multi-Grain Cheerios	G	cold	100
Nut&Honey Crunch	K	cold	120
Nutri-Grain Almond-Raisin	K	cold	140
Nutri-grain Wheat	K	cold	90
Oatmeal Raisin Crisp	G	cold	130
Post Nat. Raisin Bran	P	cold	120
Product 19	K	cold	100
Puffed Rice	Q	cold	50
Puffed Wheat	Q	cold	50
Quaker Oat Squares	Q	cold	100
Quaker Oatmeal	Q	hot	100
Raisin Bran	K	cold	120
Raisin Nut Bran	G	cold	100
Raisin Squares	K	cold	90
Rice Chex	R	cold	110
Rice Krispies	K	cold	110
Shredded Wheat	N	cold	80
Shredded Wheat 'n'Bran	N	cold	90
Shredded Wheat spoon size	N	cold	90
Smacks	K	cold	110
Special K	K	cold	110
Strawberry Fruit Wheats	N	cold	90
Total Corn Flakes	G	cold	110
Total Raisin Bran	G	cold	140
Total Whole Grain	G	cold	100
Triples	G	cold	110
Trix	G	cold	110
Wheat Chex	R	cold	100
Wheaties	G	cold	100
Wheaties Honey Gold	G	cold	110

. . .

You can remove columns from the dataset using a -.

cereal |> 
  select(-rating)

select(): Reordering

You can reorder columns inside of select().

cereal |> 
  select(name, rating, manuf, type, calories, cups, weight,
         everything())

name	rating	manuf	type	calories	cups	weight	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf
100% Bran	68.40297	N	cold	70	0.33	1.00	4	1	130	10.0	5.0	6	280	25	3
100% Natural Bran	33.98368	Q	cold	120	1.00	1.00	3	5	15	2.0	8.0	8	135	0	3
All-Bran	59.42551	K	cold	70	0.33	1.00	4	1	260	9.0	7.0	5	320	25	3
All-Bran with Extra Fiber	93.70491	K	cold	50	0.50	1.00	4	0	140	14.0	8.0	0	330	25	3
Almond Delight	34.38484	R	cold	110	0.75	1.00	2	2	200	1.0	14.0	8	-1	25	3
Apple Cinnamon Cheerios	29.50954	G	cold	110	0.75	1.00	2	2	180	1.5	10.5	10	70	25	1
Apple Jacks	33.17409	K	cold	110	1.00	1.00	2	0	125	1.0	11.0	14	30	25	2
Basic 4	37.03856	G	cold	130	0.75	1.33	3	2	210	2.0	18.0	8	100	25	3
Bran Chex	49.12025	R	cold	90	0.67	1.00	2	1	200	4.0	15.0	6	125	25	1
Bran Flakes	53.31381	P	cold	90	0.67	1.00	3	0	210	5.0	13.0	5	190	25	3
Cap'n'Crunch	18.04285	Q	cold	120	0.75	1.00	1	2	220	0.0	12.0	12	35	25	2
Cheerios	50.76500	G	cold	110	1.25	1.00	6	2	290	2.0	17.0	1	105	25	1
Cinnamon Toast Crunch	19.82357	G	cold	120	0.75	1.00	1	3	210	0.0	13.0	9	45	25	2
Clusters	40.40021	G	cold	110	0.50	1.00	3	2	140	2.0	13.0	7	105	25	3
Cocoa Puffs	22.73645	G	cold	110	1.00	1.00	1	1	180	0.0	12.0	13	55	25	2
Corn Chex	41.44502	R	cold	110	1.00	1.00	2	0	280	0.0	22.0	3	25	25	1
Corn Flakes	45.86332	K	cold	100	1.00	1.00	2	0	290	1.0	21.0	2	35	25	1
Corn Pops	35.78279	K	cold	110	1.00	1.00	1	0	90	1.0	13.0	12	20	25	2
Count Chocula	22.39651	G	cold	110	1.00	1.00	1	1	180	0.0	12.0	13	65	25	2
Cracklin' Oat Bran	40.44877	K	cold	110	0.50	1.00	3	3	140	4.0	10.0	7	160	25	3
Cream of Wheat (Quick)	64.53382	N	hot	100	1.00	1.00	3	0	80	1.0	21.0	0	-1	0	2
Crispix	46.89564	K	cold	110	1.00	1.00	2	0	220	1.0	21.0	3	30	25	3
Crispy Wheat & Raisins	36.17620	G	cold	100	0.75	1.00	2	1	140	2.0	11.0	10	120	25	3
Double Chex	44.33086	R	cold	100	0.75	1.00	2	0	190	1.0	18.0	5	80	25	3
Froot Loops	32.20758	K	cold	110	1.00	1.00	2	1	125	1.0	11.0	13	30	25	2
Frosted Flakes	31.43597	K	cold	110	0.75	1.00	1	0	200	1.0	14.0	11	25	25	1
Frosted Mini-Wheats	58.34514	K	cold	100	0.80	1.00	3	0	0	3.0	14.0	7	100	25	2
Fruit & Fibre Dates; Walnuts; and Oats	40.91705	P	cold	120	0.67	1.25	3	2	160	5.0	12.0	10	200	25	3
Fruitful Bran	41.01549	K	cold	120	0.67	1.33	3	0	240	5.0	14.0	12	190	25	3
Fruity Pebbles	28.02576	P	cold	110	0.75	1.00	1	1	135	0.0	13.0	12	25	25	2
Golden Crisp	35.25244	P	cold	100	0.88	1.00	2	0	45	0.0	11.0	15	40	25	1
Golden Grahams	23.80404	G	cold	110	0.75	1.00	1	1	280	0.0	15.0	9	45	25	2
Grape Nuts Flakes	52.07690	P	cold	100	0.88	1.00	3	1	140	3.0	15.0	5	85	25	3
Grape-Nuts	53.37101	P	cold	110	0.25	1.00	3	0	170	3.0	17.0	3	90	25	3
Great Grains Pecan	45.81172	P	cold	120	0.33	1.00	3	3	75	3.0	13.0	4	100	25	3
Honey Graham Ohs	21.87129	Q	cold	120	1.00	1.00	1	2	220	1.0	12.0	11	45	25	2
Honey Nut Cheerios	31.07222	G	cold	110	0.75	1.00	3	1	250	1.5	11.5	10	90	25	1
Honey-comb	28.74241	P	cold	110	1.33	1.00	1	0	180	0.0	14.0	11	35	25	1
Just Right Crunchy Nuggets	36.52368	K	cold	110	1.00	1.00	2	1	170	1.0	17.0	6	60	100	3
Just Right Fruit & Nut	36.47151	K	cold	140	0.75	1.30	3	1	170	2.0	20.0	9	95	100	3
Kix	39.24111	G	cold	110	1.50	1.00	2	1	260	0.0	21.0	3	40	25	2
Life	45.32807	Q	cold	100	0.67	1.00	4	2	150	2.0	12.0	6	95	25	2
Lucky Charms	26.73451	G	cold	110	1.00	1.00	2	1	180	0.0	12.0	12	55	25	2
Maypo	54.85092	A	hot	100	1.00	1.00	4	1	0	0.0	16.0	3	95	25	2
Muesli Raisins; Dates; & Almonds	37.13686	R	cold	150	1.00	1.00	4	3	95	3.0	16.0	11	170	25	3
Muesli Raisins; Peaches; & Pecans	34.13976	R	cold	150	1.00	1.00	4	3	150	3.0	16.0	11	170	25	3
Mueslix Crispy Blend	30.31335	K	cold	160	0.67	1.50	3	2	150	3.0	17.0	13	160	25	3
Multi-Grain Cheerios	40.10596	G	cold	100	1.00	1.00	2	1	220	2.0	15.0	6	90	25	1
Nut&Honey Crunch	29.92429	K	cold	120	0.67	1.00	2	1	190	0.0	15.0	9	40	25	2
Nutri-Grain Almond-Raisin	40.69232	K	cold	140	0.67	1.33	3	2	220	3.0	21.0	7	130	25	3
Nutri-grain Wheat	59.64284	K	cold	90	1.00	1.00	3	0	170	3.0	18.0	2	90	25	3
Oatmeal Raisin Crisp	30.45084	G	cold	130	0.50	1.25	3	2	170	1.5	13.5	10	120	25	3
Post Nat. Raisin Bran	37.84059	P	cold	120	0.67	1.33	3	1	200	6.0	11.0	14	260	25	3
Product 19	41.50354	K	cold	100	1.00	1.00	3	0	320	1.0	20.0	3	45	100	3
Puffed Rice	60.75611	Q	cold	50	1.00	0.50	1	0	0	0.0	13.0	0	15	0	3
Puffed Wheat	63.00565	Q	cold	50	1.00	0.50	2	0	0	1.0	10.0	0	50	0	3
Quaker Oat Squares	49.51187	Q	cold	100	0.50	1.00	4	1	135	2.0	14.0	6	110	25	3
Quaker Oatmeal	50.82839	Q	hot	100	0.67	1.00	5	2	0	2.7	-1.0	-1	110	0	1
Raisin Bran	39.25920	K	cold	120	0.75	1.33	3	1	210	5.0	14.0	12	240	25	2
Raisin Nut Bran	39.70340	G	cold	100	0.50	1.00	3	2	140	2.5	10.5	8	140	25	3
Raisin Squares	55.33314	K	cold	90	0.50	1.00	2	0	0	2.0	15.0	6	110	25	3
Rice Chex	41.99893	R	cold	110	1.13	1.00	1	0	240	0.0	23.0	2	30	25	1
Rice Krispies	40.56016	K	cold	110	1.00	1.00	2	0	290	0.0	22.0	3	35	25	1
Shredded Wheat	68.23588	N	cold	80	1.00	0.83	2	0	0	3.0	16.0	0	95	0	1
Shredded Wheat 'n'Bran	74.47295	N	cold	90	0.67	1.00	3	0	0	4.0	19.0	0	140	0	1
Shredded Wheat spoon size	72.80179	N	cold	90	0.67	1.00	3	0	0	3.0	20.0	0	120	0	1
Smacks	31.23005	K	cold	110	0.75	1.00	2	1	70	1.0	9.0	15	40	25	2
Special K	53.13132	K	cold	110	1.00	1.00	6	0	230	1.0	16.0	3	55	25	1
Strawberry Fruit Wheats	59.36399	N	cold	90	1.00	1.00	2	0	15	3.0	15.0	5	90	25	2
Total Corn Flakes	38.83975	G	cold	110	1.00	1.00	2	1	200	0.0	21.0	3	35	100	3
Total Raisin Bran	28.59278	G	cold	140	1.00	1.50	3	1	190	4.0	15.0	14	230	100	3
Total Whole Grain	46.65884	G	cold	100	1.00	1.00	3	1	200	3.0	16.0	3	110	100	3
Triples	39.10617	G	cold	110	0.75	1.00	2	1	250	0.0	21.0	3	60	25	3
Trix	27.75330	G	cold	110	1.00	1.00	1	1	140	0.0	13.0	12	25	25	2
Wheat Chex	49.78744	R	cold	100	0.67	1.00	3	1	230	3.0	17.0	3	115	25	1
Wheaties	51.59219	G	cold	100	1.00	1.00	3	1	200	3.0	17.0	3	110	25	1
Wheaties Honey Gold	36.18756	G	cold	110	0.75	1.00	2	1	200	1.0	16.0	8	60	25	1

select(): Handy Helpers!

• everything() – selects all columns that you have not already specified
• starts_with() – selects columns with names that start with the specified string
• ends_with() – selects columns with names that end with the specified string
• contains() – selects columns with names that contain the specified string
• where() – applies a function to all variables and selects those for which the function returns TRUE

See the help file for select()!

rename()

• You can rename columns with select(), but all columns not specified will be dropped.
  • Using the rename() function is easier!

cereal |> 
  rename(temp = type)

name	manuf	temp	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756

mutate()

knitr::include_graphics("https://github.com/allisonhorst/stats-illustrations/raw/main/rstats-artwork/dplyr_mutate.png")

(Allison Horst)

mutate()

The dataset gets mutated to either include a new variable…

cereal |> 
  mutate(potass_per_cup = potass / cups)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating	potass_per_cup
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297	848.484848
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368	135.000000
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551	969.696970
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491	660.000000
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484	-1.333333
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954	93.333333
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409	30.000000
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856	133.333333
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025	186.567164
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381	283.582090
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285	46.666667
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500	84.000000
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357	60.000000
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021	210.000000
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645	55.000000
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502	25.000000
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332	35.000000
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279	20.000000
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651	65.000000
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877	320.000000
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382	-1.000000
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564	30.000000
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620	160.000000
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086	106.666667
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758	30.000000
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597	33.333333
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514	125.000000
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705	298.507463
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549	283.582090
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576	33.333333
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244	45.454546
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404	60.000000
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690	96.590909
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101	360.000000
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172	303.030303
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129	45.000000
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222	120.000000
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241	26.315790
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368	60.000000
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151	126.666667
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111	26.666667
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807	141.791045
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451	55.000000
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092	95.000000
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686	170.000000
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976	170.000000
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335	238.805970
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596	90.000000
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429	59.701493
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232	194.029851
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284	90.000000
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084	240.000000
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059	388.059702
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354	45.000000
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611	15.000000
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565	50.000000
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187	220.000000
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839	164.179104
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920	320.000000
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340	280.000000
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314	220.000000
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893	26.548673
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016	35.000000
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588	95.000000
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295	208.955224
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179	179.104478
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005	53.333333
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132	55.000000
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399	90.000000
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975	35.000000
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278	230.000000
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884	110.000000
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617	80.000000
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330	25.000000
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744	171.641791
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219	110.000000
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756	80.000000

. . .

…OR revise an existing variable.

cereal |> 
  mutate(shelf = as.factor(shelf))

mutate(): Handy Helpers!

Applies vectorized functions to columns

• if_else() or case_when() – shortcut for if-else loop
• as.factor(), as.numeric(), etc. – change variable type
• +, -, *, / – basic mathematical operations
• %% – modulo (returns the remainder when doing division)

summarize()

summarize()

We can calculate summaries of variables in the data.

. . .

cereal |> 
  summarise(mean_fiber = mean(fiber))

  mean_fiber
1   2.151948

. . .

Or multiple summaries at the same time.

cereal |> 
summarise(mean_fiber = mean(fiber),
          num_cereals = n(),
          mean_sugar = mean(sugars))

  mean_fiber num_cereals mean_sugar
1   2.151948          77   6.922078

. . .

Note

summarize() and summarise() are synonyms!

summarize(): Handy Helpers!

Applies summary functions to columns to create a new table (function takes a vector and returns a single value)

• mean(), median(), sd(), sum()
• min(), max()
• n(), n_distinct() – counts the number of (distinct) elements
• first(), last(), nth() – extract the first, last, or nth element
• across() – apply a function across columns

group_by()

summarize() is almost always paired with group_by()!

knitr::include_graphics("https://raw.githubusercontent.com/allisonhorst/stats-illustrations/main/rstats-blanks/ungroup_blank.png")

(Allison Horst)

group_by()

Separate the data into different groups based on a categorical variable.

. . .

• The data gets grouped, but nothing happens externally if used on its own.

cereal |> 
  group_by(type)

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756

group_by() + summarize()!

1. group_by a variable (or multiple variables)
2. summarize a variable (or multiple variables) within the groups

cereal |> 
  group_by(manuf) |> 
  summarise(mean_sugar = mean(sugars))

manuf	mean_sugar
A	3.000000
G	7.954546
K	7.565217
N	1.833333
P	8.777778
Q	5.250000
R	6.125000

group_by() + mutate()!

1. group_by a variable (or multiple variables)
2. mutate a variable (or multiple variables) within the groups

cereal |> 
  group_by(manuf) |> 
  mutate(mean_sugar = mean(sugars))

name	manuf	type	calories	protein	fat	sodium	fiber	carbo	sugars	potass	vitamins	shelf	weight	cups	rating	mean_sugar
100% Bran	N	cold	70	4	1	130	10.0	5.0	6	280	25	3	1.00	0.33	68.40297	1.833333
100% Natural Bran	Q	cold	120	3	5	15	2.0	8.0	8	135	0	3	1.00	1.00	33.98368	5.250000
All-Bran	K	cold	70	4	1	260	9.0	7.0	5	320	25	3	1.00	0.33	59.42551	7.565217
All-Bran with Extra Fiber	K	cold	50	4	0	140	14.0	8.0	0	330	25	3	1.00	0.50	93.70491	7.565217
Almond Delight	R	cold	110	2	2	200	1.0	14.0	8	-1	25	3	1.00	0.75	34.38484	6.125000
Apple Cinnamon Cheerios	G	cold	110	2	2	180	1.5	10.5	10	70	25	1	1.00	0.75	29.50954	7.954546
Apple Jacks	K	cold	110	2	0	125	1.0	11.0	14	30	25	2	1.00	1.00	33.17409	7.565217
Basic 4	G	cold	130	3	2	210	2.0	18.0	8	100	25	3	1.33	0.75	37.03856	7.954546
Bran Chex	R	cold	90	2	1	200	4.0	15.0	6	125	25	1	1.00	0.67	49.12025	6.125000
Bran Flakes	P	cold	90	3	0	210	5.0	13.0	5	190	25	3	1.00	0.67	53.31381	8.777778
Cap'n'Crunch	Q	cold	120	1	2	220	0.0	12.0	12	35	25	2	1.00	0.75	18.04285	5.250000
Cheerios	G	cold	110	6	2	290	2.0	17.0	1	105	25	1	1.00	1.25	50.76500	7.954546
Cinnamon Toast Crunch	G	cold	120	1	3	210	0.0	13.0	9	45	25	2	1.00	0.75	19.82357	7.954546
Clusters	G	cold	110	3	2	140	2.0	13.0	7	105	25	3	1.00	0.50	40.40021	7.954546
Cocoa Puffs	G	cold	110	1	1	180	0.0	12.0	13	55	25	2	1.00	1.00	22.73645	7.954546
Corn Chex	R	cold	110	2	0	280	0.0	22.0	3	25	25	1	1.00	1.00	41.44502	6.125000
Corn Flakes	K	cold	100	2	0	290	1.0	21.0	2	35	25	1	1.00	1.00	45.86332	7.565217
Corn Pops	K	cold	110	1	0	90	1.0	13.0	12	20	25	2	1.00	1.00	35.78279	7.565217
Count Chocula	G	cold	110	1	1	180	0.0	12.0	13	65	25	2	1.00	1.00	22.39651	7.954546
Cracklin' Oat Bran	K	cold	110	3	3	140	4.0	10.0	7	160	25	3	1.00	0.50	40.44877	7.565217
Cream of Wheat (Quick)	N	hot	100	3	0	80	1.0	21.0	0	-1	0	2	1.00	1.00	64.53382	1.833333
Crispix	K	cold	110	2	0	220	1.0	21.0	3	30	25	3	1.00	1.00	46.89564	7.565217
Crispy Wheat & Raisins	G	cold	100	2	1	140	2.0	11.0	10	120	25	3	1.00	0.75	36.17620	7.954546
Double Chex	R	cold	100	2	0	190	1.0	18.0	5	80	25	3	1.00	0.75	44.33086	6.125000
Froot Loops	K	cold	110	2	1	125	1.0	11.0	13	30	25	2	1.00	1.00	32.20758	7.565217
Frosted Flakes	K	cold	110	1	0	200	1.0	14.0	11	25	25	1	1.00	0.75	31.43597	7.565217
Frosted Mini-Wheats	K	cold	100	3	0	0	3.0	14.0	7	100	25	2	1.00	0.80	58.34514	7.565217
Fruit & Fibre Dates; Walnuts; and Oats	P	cold	120	3	2	160	5.0	12.0	10	200	25	3	1.25	0.67	40.91705	8.777778
Fruitful Bran	K	cold	120	3	0	240	5.0	14.0	12	190	25	3	1.33	0.67	41.01549	7.565217
Fruity Pebbles	P	cold	110	1	1	135	0.0	13.0	12	25	25	2	1.00	0.75	28.02576	8.777778
Golden Crisp	P	cold	100	2	0	45	0.0	11.0	15	40	25	1	1.00	0.88	35.25244	8.777778
Golden Grahams	G	cold	110	1	1	280	0.0	15.0	9	45	25	2	1.00	0.75	23.80404	7.954546
Grape Nuts Flakes	P	cold	100	3	1	140	3.0	15.0	5	85	25	3	1.00	0.88	52.07690	8.777778
Grape-Nuts	P	cold	110	3	0	170	3.0	17.0	3	90	25	3	1.00	0.25	53.37101	8.777778
Great Grains Pecan	P	cold	120	3	3	75	3.0	13.0	4	100	25	3	1.00	0.33	45.81172	8.777778
Honey Graham Ohs	Q	cold	120	1	2	220	1.0	12.0	11	45	25	2	1.00	1.00	21.87129	5.250000
Honey Nut Cheerios	G	cold	110	3	1	250	1.5	11.5	10	90	25	1	1.00	0.75	31.07222	7.954546
Honey-comb	P	cold	110	1	0	180	0.0	14.0	11	35	25	1	1.00	1.33	28.74241	8.777778
Just Right Crunchy Nuggets	K	cold	110	2	1	170	1.0	17.0	6	60	100	3	1.00	1.00	36.52368	7.565217
Just Right Fruit & Nut	K	cold	140	3	1	170	2.0	20.0	9	95	100	3	1.30	0.75	36.47151	7.565217
Kix	G	cold	110	2	1	260	0.0	21.0	3	40	25	2	1.00	1.50	39.24111	7.954546
Life	Q	cold	100	4	2	150	2.0	12.0	6	95	25	2	1.00	0.67	45.32807	5.250000
Lucky Charms	G	cold	110	2	1	180	0.0	12.0	12	55	25	2	1.00	1.00	26.73451	7.954546
Maypo	A	hot	100	4	1	0	0.0	16.0	3	95	25	2	1.00	1.00	54.85092	3.000000
Muesli Raisins; Dates; & Almonds	R	cold	150	4	3	95	3.0	16.0	11	170	25	3	1.00	1.00	37.13686	6.125000
Muesli Raisins; Peaches; & Pecans	R	cold	150	4	3	150	3.0	16.0	11	170	25	3	1.00	1.00	34.13976	6.125000
Mueslix Crispy Blend	K	cold	160	3	2	150	3.0	17.0	13	160	25	3	1.50	0.67	30.31335	7.565217
Multi-Grain Cheerios	G	cold	100	2	1	220	2.0	15.0	6	90	25	1	1.00	1.00	40.10596	7.954546
Nut&Honey Crunch	K	cold	120	2	1	190	0.0	15.0	9	40	25	2	1.00	0.67	29.92429	7.565217
Nutri-Grain Almond-Raisin	K	cold	140	3	2	220	3.0	21.0	7	130	25	3	1.33	0.67	40.69232	7.565217
Nutri-grain Wheat	K	cold	90	3	0	170	3.0	18.0	2	90	25	3	1.00	1.00	59.64284	7.565217
Oatmeal Raisin Crisp	G	cold	130	3	2	170	1.5	13.5	10	120	25	3	1.25	0.50	30.45084	7.954546
Post Nat. Raisin Bran	P	cold	120	3	1	200	6.0	11.0	14	260	25	3	1.33	0.67	37.84059	8.777778
Product 19	K	cold	100	3	0	320	1.0	20.0	3	45	100	3	1.00	1.00	41.50354	7.565217
Puffed Rice	Q	cold	50	1	0	0	0.0	13.0	0	15	0	3	0.50	1.00	60.75611	5.250000
Puffed Wheat	Q	cold	50	2	0	0	1.0	10.0	0	50	0	3	0.50	1.00	63.00565	5.250000
Quaker Oat Squares	Q	cold	100	4	1	135	2.0	14.0	6	110	25	3	1.00	0.50	49.51187	5.250000
Quaker Oatmeal	Q	hot	100	5	2	0	2.7	-1.0	-1	110	0	1	1.00	0.67	50.82839	5.250000
Raisin Bran	K	cold	120	3	1	210	5.0	14.0	12	240	25	2	1.33	0.75	39.25920	7.565217
Raisin Nut Bran	G	cold	100	3	2	140	2.5	10.5	8	140	25	3	1.00	0.50	39.70340	7.954546
Raisin Squares	K	cold	90	2	0	0	2.0	15.0	6	110	25	3	1.00	0.50	55.33314	7.565217
Rice Chex	R	cold	110	1	0	240	0.0	23.0	2	30	25	1	1.00	1.13	41.99893	6.125000
Rice Krispies	K	cold	110	2	0	290	0.0	22.0	3	35	25	1	1.00	1.00	40.56016	7.565217
Shredded Wheat	N	cold	80	2	0	0	3.0	16.0	0	95	0	1	0.83	1.00	68.23588	1.833333
Shredded Wheat 'n'Bran	N	cold	90	3	0	0	4.0	19.0	0	140	0	1	1.00	0.67	74.47295	1.833333
Shredded Wheat spoon size	N	cold	90	3	0	0	3.0	20.0	0	120	0	1	1.00	0.67	72.80179	1.833333
Smacks	K	cold	110	2	1	70	1.0	9.0	15	40	25	2	1.00	0.75	31.23005	7.565217
Special K	K	cold	110	6	0	230	1.0	16.0	3	55	25	1	1.00	1.00	53.13132	7.565217
Strawberry Fruit Wheats	N	cold	90	2	0	15	3.0	15.0	5	90	25	2	1.00	1.00	59.36399	1.833333
Total Corn Flakes	G	cold	110	2	1	200	0.0	21.0	3	35	100	3	1.00	1.00	38.83975	7.954546
Total Raisin Bran	G	cold	140	3	1	190	4.0	15.0	14	230	100	3	1.50	1.00	28.59278	7.954546
Total Whole Grain	G	cold	100	3	1	200	3.0	16.0	3	110	100	3	1.00	1.00	46.65884	7.954546
Triples	G	cold	110	2	1	250	0.0	21.0	3	60	25	3	1.00	0.75	39.10617	7.954546
Trix	G	cold	110	1	1	140	0.0	13.0	12	25	25	2	1.00	1.00	27.75330	7.954546
Wheat Chex	R	cold	100	3	1	230	3.0	17.0	3	115	25	1	1.00	0.67	49.78744	6.125000
Wheaties	G	cold	100	3	1	200	3.0	17.0	3	110	25	1	1.00	1.00	51.59219	7.954546
Wheaties Honey Gold	G	cold	110	2	1	200	1.0	16.0	8	60	25	1	1.00	0.75	36.18756	7.954546

mutate() vs summarise()

group_by() + summarize() collapses the data.

• You will only have one row per group remaining.
• You will only have one column for each grouping variable, plus each variable that you specified in summarize.

. . .

group_by() + mutate() does not.

• You will have the full number of rows remaining.
• You will have the full number of columns remaining, plus additional columns you created.

mutate() vs summarise()

summarise()

mutate()

Quick check

How many rows and columns will each of these data frames have?

cereal |> 
  group_by(manuf) |> 
  mutate(fiber_carb_rat = mean(fiber / carbo))

cereal |> 
  group_by(manuf) |> 
  summarize(fiber_carb_rat = mean(fiber / carbo))

Tip

The cereal data starts with 77 rows and 16 columns. There are 7 manufacturers in the data.

ungroup()

The ungroup() function will remove the internal grouping in your data.

• Useful if you want to create a different grouping
• This is not something that you always need to do.
• Tip: if you are getting unexpected output downstream from a group_by() statement, try ungrouping your data!

Putting it All Together

Glue it all together!

cereal |> 
  filter(type == "cold") |> 
  mutate(potass_per_cup = potass / cups) |> 
  group_by(manuf) |> 
  summarise(mean_potass_per_cup = mean(potass_per_cup))

manuf	mean_potass_per_cup
G	109.1970
K	175.3978
N	284.3089
P	203.8749
Q	93.3511
R	106.8864

Save your changes!

If you need to use your manipulated data in another part of your code, make sure you assign your new dataset to a variable!

cereal_summary <- cereal |> 
  filter(type == "cold") |> 
  mutate(potass_per_cup = potas / cups) |> 
  group_by(manuf) |> 
  summarise(mean_potass_per_cup = mean(potass_per_cup))

If you don’t need that table again… no need to save a new object

Code Formatting

Similar to the + formatting in ggplot, do not continue a line after writing a |>!

Bad Practice

cereal |> group_by(type) |> summarise(mean_fiber = mean(fiber), num_cereals = n(), mean_sugar = mean(sugars))

Good Practice

cereal |> 
  group_by(type) |> 
  summarise(mean_fiber = mean(fiber), 
            num_cereals = n(),
            mean_sugar = mean(sugars))

Now you!

In your group implement the dplyr pipelines to address the three questions from the beginning of class:

1. What is the ratio of fiber to sugars in each cereal?

2. Create a new dataset that only has Nabisco cereals and displays the protein, fat, and sodium in each.

3. Create a table that shows, for each manufacturer the average and standard deviation of the grams of sugar in their cereals, along with how many cereals are in the data for each manufacturer. Order the table from most sugar (on average) to least.

PA 3: Identify the Mystery College

Today you will use the dplyr package to clean some data and then use that cleaned data to figure out what college Margaret has been accepted to.

Submit the full name of the college Margaret will attend to the Canvas Quiz.

To do…

• PA 3: Identify the Mystery College
  • Due Tuesday 4/14 at 11:59pm
• Reading and Review
  • Note that there is an Extra Data Ethics Reading
  • Read before class on Wednesday
• Lab 3: Teacher Evaluations
  • Due Sunday 4/19 at 11:59 pm