PA 8.1: The Twelve Days of Christmas

Starter Functions

Introduction

The song The Twelve Days of Christmas, written around 1780, tells the tale of the many gifts one person receives in the days after Christmas (link to lyrics).

Note

You can watch a video of The Twelve Days of Christmas being performed at the Cambria Christmas Market.

The gifts in this song repeat and compound. For example, on the first day, the narrator receives:

A partridge in a pear tree.

On the twelfth day, they receive:

Twelve Drummers Drumming
Eleven Pipers Piping
Ten Lords a Leaping
Nine Ladies Waiting
Eight Maids a Milking
Seven Swans a Swimming
Six Geese a Laying
Five Golden Rings
Four Calling Birds
Three French Hens
Two Turtle Doves
And a Partridge in a Pear Tree

This week, your task is to write functions that will automatically sing this very repetitive song. In the practice activity, we will start by writing two helper functions.

Dataset

Save the xmas.csv on your computer (in a place that makes sense!) and edit the provided code to load a dataset called xmas. This dataset contains the crucial information about each gift in the song. We will use this dataset to test our functions as we work on them.

xmas <- read.csv("xmas.csv")

Error in file(file, "rt"): cannot open the connection

Advice

Workflow

Make smaller versions of the xmas dataset (e.g., the first two days) to test your functions before testing them on the full data set.
Your functions should reference each other. That is, don’t duplicate code; use earlier, smaller functions inside your larger functions.

Build from small pieces

If you have some trouble getting started, I recommend writing a function that works in one case (e.g., for day 3), and then trying to generalize it.

Don’t sweat the small stuff

There’s a lot you can do to polish the way the song prints, but we’re going to leave that be.
At this point, don’t get bogged down in details like how the song displays, or small grammar rules (like commas!).

1 Plurals – `pluralize_gift()`

In the xmas dataset, the gifts are listed as singular. For example, on day 5, the narrator in the song receives “five golden rings”, but the entry in the dataset for gift 5 simply says “ring”.

Hint

The gifts on days six and nine have unusual pluralization (not just adding an “s”). You may assume that in any other dataset we might apply this function to, there will be no additional special cases beyond these two types.

Important!

You should absolutely not hard-code anything into this function. It should work in general, not just for the items in the traditional version of The Twelve Days of Christmas.

For example, the word “ring” should not appear anywhere in the function. I should be able to give your function any gift and get back the plural of that gift.

Complete the pluralize_gift() function below. This function should take in a gift (or a vector of gifts) and return the appropriate plural(s).

# Function that takes a noun and makes it plural
# Arguments: gift -- a string or vector of strings
# Return:    a string or vector of strings with the pluralized words

pluralize_gift <- function(gift){

  
  

  return(gift)
}

Test Your Function

Try your function on a smaller and then on the full gift dataset.

# If your function is vectorized:
pluralize_gift(xmas$Gift.Item)

Error: object 'xmas' not found

# If your function is not vectorized:
map_chr(xmas$Gift.Item, pluralize_gift)

Error: object 'xmas' not found

2 Creating Sentences – `make_phrase()`

Write a function called make_phrase() that takes in the necessary information and returns a phrase. For example:

make_phrase(num       = 10,
            item      = "lord", 
            verb      = "a-leaping", 
            adjective = "", 
            location  = "")

should return

"ten lords a-leaping"

Tip

The Day.in.Words variable isn’t quite what you want. You want 12 to say "twelve" not "twelfth". I suggest using the english package to create number words from number digits.

If you get a frustrating error from the english package, try wrapping as.character() around your new number word.

make_phrase <- function(num, item, verb, adjective, location) {
  
  ## Step 1: Replace NAs with blank strings.
  verb <- str_replace_na(verb, "")
  
  
  ## Step 2: If the day number is larger than 1, the gift must be plural.
  ### Hint: call the function you created above!
  
  
  ## Step 3: Figure out if the gift starts with a vowel.
  
  
  ## Step 4: For day 1, if the gift starts with a vowel, make day_word be "an" and if the gift does not start with a vowel, make the day_word be "a" (e.g. a partridge in a pear tree).
  ### For the other days, make day_word be the number word (e.g. ten lords a-leaping).
  ### See the tip above about turning numbers into words (e.g. 10 into ten).
  day_word
  
  ## Step 5: Glue all of the pieces together into one string and return!
  
  return(phrase)
}

Test Your Function

Try your function out on the xmas data by making a new variable containing the daily phrases. I’ve provided you with skeleton code to iterate through each row of the dataset – all you need to do is provide the necessary inputs.

xmas2 <- xmas |> 
  mutate(full_phrase = pmap_chr(.l = list(num       = ______,
                                          item      = ______, 
                                          verb      = ______, 
                                          adjective = ______, 
                                          location  = ______), 
                                .f = make_phrase))
xmas2

Error in parse(text = input): <text>:2:56: unexpected input
1: xmas2 <- xmas |> 
2:   mutate(full_phrase = pmap_chr(.l = list(num       = __
                                                          ^

Canvas Submission

Your full_phrase column is the answer to this week’s practice activity.

Take a screenshot of your full_phrase column to show me the phrases you made!

--- title: "PA 8.1: The Twelve Days of Christmas" subtitle: "Starter Functions" format: html: code-tools: true toc: true number-sections: true editor: source execute: error: true echo: true message: false warning: false --- ```{r setup} #| include: false library(tidyverse) library(glue) ``` [Download starter .qmd template](../student-versions/pas/pa8-1.qmd) [Download xmas.csv data](_data/xmas.csv) ## Introduction {-} The song *The Twelve Days of Christmas*, written around 1780, tells the tale of the many gifts one person receives in the days after Christmas ([link to lyrics](https://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song))). ::: callout-note You can watch a video of *The Twelve Days of Christmas* being performed at the [Cambria Christmas Market](https://www.youtube.com/watch?v=_N9UeQRf_aQ&ab_channel=SanLuisObispoCountyVisitorsGuide). ::: The gifts in this song repeat and compound. For example, on the first day, the narrator receives: A partridge in a pear tree. On the twelfth day, they receive: Twelve Drummers Drumming Eleven Pipers Piping Ten Lords a Leaping Nine Ladies Waiting Eight Maids a Milking Seven Swans a Swimming Six Geese a Laying Five Golden Rings Four Calling Birds Three French Hens Two Turtle Doves And a Partridge in a Pear Tree This week, your task is to write functions that will automatically sing this very repetitive song. In the practice activity, we will start by writing **two helper functions**. ## Dataset {-} Save the `xmas.csv` on your computer (in a place that makes sense!) and edit the provided code to load a dataset called `xmas`. This dataset contains the crucial information about each gift in the song. We will use this dataset to test our functions as we work on them. ```{r} xmas <- read.csv("xmas.csv") ``` ::: callout-tip ### Advice ##### Workflow {-} + Make smaller versions of the `xmas` dataset (e.g., the first two days) to test your functions *before* testing them on the full data set. + Your functions should reference each other. That is, don't duplicate code; use earlier, smaller functions inside your larger functions. ##### Build from small pieces {-} + If you have some trouble getting started, I recommend writing a function that works in one case (e.g., for day 3), and then trying to generalize it. ##### Don't sweat the small stuff {-} + There's a lot you can do to polish the way the song prints, but we're going to leave that be. + At this point, don't get bogged down in details like how the song displays, or small grammar rules (like commas!). ::: ## Plurals -- `pluralize_gift()` In the `xmas` dataset, the gifts are listed as singular. For example, on day 5, the narrator in the song receives "five golden rings", but the entry in the dataset for gift 5 simply says "ring". ::: callout-tip # Hint The gifts on days six and nine have unusual pluralization (not just adding an "s"). You may assume that in any other dataset we might apply this function to, there will be **no** additional special cases beyond these two types. ::: ::: callout-caution #### Important! You should **absolutely not** hard-code anything into this function. It should work in general, not just for the items in the traditional version of *The Twelve Days of Christmas*. For example, the word "ring" should not appear anywhere in the function. I should be able to give your function **any gift** and get back the plural of that gift. ::: Complete the `pluralize_gift()` function below. This function should take in a gift (or a vector of gifts) and return the appropriate plural(s). ```{r pluralize-function} # Function that takes a noun and makes it plural # Arguments: gift -- a string or vector of strings # Return: a string or vector of strings with the pluralized words pluralize_gift <- function(gift){ return(gift) } ``` ::: callout-note ### Test Your Function Try your function on a smaller and then on the full gift dataset. ```{r pluralize-test} # If your function is vectorized: pluralize_gift(xmas$Gift.Item) # If your function is not vectorized: map_chr(xmas$Gift.Item, pluralize_gift) ``` ::: ## Creating Sentences -- `make_phrase()` Write a function called `make_phrase()` that takes in the necessary information and returns a phrase. For example: make_phrase(num = 10, item = "lord", verb = "a-leaping", adjective = "", location = "") should return "ten lords a-leaping" ::: callout-tip The `Day.in.Words` variable isn't quite what you want. You want `12` to say `"twelve"` **not** `"twelfth"`. I suggest using the `english` package to create number words from number digits. If you get a frustrating error from the `english` package, try wrapping `as.character()` around your new number word. ::: ```{r phrase-function} make_phrase <- function(num, item, verb, adjective, location) { ## Step 1: Replace NAs with blank strings. verb <- str_replace_na(verb, "") ## Step 2: If the day number is larger than 1, the gift must be plural. ### Hint: call the function you created above! ## Step 3: Figure out if the gift starts with a vowel. ## Step 4: For day 1, if the gift starts with a vowel, make day_word be "an" and if the gift does not start with a vowel, make the day_word be "a" (e.g. a partridge in a pear tree). ### For the other days, make day_word be the number word (e.g. ten lords a-leaping). ### See the tip above about turning numbers into words (e.g. 10 into ten). day_word ## Step 5: Glue all of the pieces together into one string and return! return(phrase) } ``` ::: callout-note ### Test Your Function Try your function out on the `xmas` data by making a new variable containing the daily phrases. I've provided you with skeleton code to iterate through each row of the dataset -- all you need to do is provide the necessary inputs. ```{r} xmas2 <- xmas |> mutate(full_phrase = pmap_chr(.l = list(num = ______, item = ______, verb = ______, adjective = ______, location = ______), .f = make_phrase)) xmas2 ``` ::: ## Canvas Submission {-} > Your `full_phrase` column is the answer to this week's practice activity. > > Take a screenshot of your `full_phrase` column to show me the phrases you made!

Introduction

Dataset

Workflow

Build from small pieces

Don’t sweat the small stuff

1 Plurals – pluralize_gift()

2 Creating Sentences – make_phrase()

Canvas Submission

1 Plurals – `pluralize_gift()`

2 Creating Sentences – `make_phrase()`