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title: "Tidyverse Fun - Part 1"
description: |
First part in a series of doing useful tasks with
the `Tidyverse`. This time generating Oxford Comma
triples and generating sequentially numbered BibTeX
- tidyverse
- rstats
- name: Shamindra Shrotriya
date: 07-15-2019
preview: images/logo-01.jpg
slug: shrotriya2019tidyfunpt1
bibliography: ../../refs.bib
self_contained: false
toc: true
toc_depth: 2
```{r setup_01_01, include=FALSE, cache=TRUE}
knitr::opts_chunk$set(echo = TRUE)
## Task 1: Generating Oxford Comma Triples
### The central problem
Based on a fun conversation with my statistics cohort over dinner we got to
discussing the famous *Oxford Comma* [@wiki_serial_comma] (or *Serial Comma*
depending on your persuasion). I've never really adopted the use but my friends
made a compelling argument on it's apparent general lack of ambiguity when
applied appropriately.
We will use the Oxford comma on the famously *ambiguous* phrase (here used
without the Oxford Comma before _leaves_):
> Eats, shoots and leaves
After adding in the Oxford Comma this would become:
> Eats, shoots, and leaves
**Goal:** A fun experiment would be to generate *all permutations* of this
phrase with and without the Oxford Comma using `R` and specifically the
`tidyverse` packages.
### Generating all word-triple permutations the `tidy` way
Let's load our required packages
```{r setup_oxc_01_01, echo=TRUE, cache=TRUE}
Let's also define our unique global word values used to construct the required
```{r setup_oxc_01_02, echo=TRUE, cache=TRUE}
WORD_VALS <- c("eats", "shoots", "leaves")
Generate all unique 3-word permutations _without replacement_ from the three
unique words. We'll create a helper function to check that a vector of words is
```{r setup_oxc_01_03, echo=TRUE, cache=TRUE}
is_unq_perm <- function(word1, word2, word3){
words_vec <- c(word1, word2, word3)
base::return(length(words_vec) - length(unique(words_vec)) == 0)
We can now simply generate every possible triple _with replacement_ using the
`tidyr::crossing` function. We proceed to _filter_ these $3^3 = 27$ triples
for unique triples using our `is_unq_perm` helper function applied _row-by-row_
using `purrr::pmap_lgl`. The `_lgl` simply returns a `TRUE/FALSE` logical value
as intended by the applied function.
<aside> __Note:__ The `tidyr::crossing` generates a *Cartesian product* of all
the 3 word triples, very handy</aside>
```{r setup_oxc_01_04, echo=TRUE, cache=TRUE}
# Generate the unique word-triples
all_perms <- tidyr::crossing(word1 = WORD_VALS,
word2 = WORD_VALS,
word3 = WORD_VALS) %>%
dplyr::mutate(.data = .,
is_unq_perm = purrr::pmap_lgl(.l = .,
is_unq_perm)) %>%
dplyr::filter(.data = ., is_unq_perm) %>%
# Display output in a nice centered table
all_perms %>%
knitr::kable(x = ., align = 'c',
col.names = c("Word 1",
"Word 2",
"Word 3"))
Great - that part is done! Now we just need to generate for each triple of
words an oxford comma and non-oxford comma version. This is done easily using
the amazing `glue` package as seen below:
```{r setup_oxc_01_05, cache=TRUE, echo=TRUE}
exprs <- all_perms %>%
dplyr::mutate(non_oxford_comma =
glue::glue_data(.x = .,
"{word1}, {word2} and {word3}"),
oxford_comma =
glue::glue_data(.x = .,
"{word1}, {word2}, and {word3}")) %>%
dplyr::select(non_oxford_comma, oxford_comma)
We can display the side-by-side output of the Non-Oxford Comma vs. Oxford comma
for the $6$ generated triples as follows:
```{r setup_oxc_01_06, cache=TRUE, echo=TRUE}
# Display output in a nice centered table
exprs %>%
knitr::kable(x = .,
align = 'c',
col.names = c("Non-Oxford Comma",
"Oxford Comma"))
So there you have it. Have fun generating your own version of Oxford Comma
triples to engage in civil discussions with your fellow grammar focused friends
`r emo::ji("smile")`.
## Task 2: Generating Sequentially Numbered BibTeX Entries
### The central problem
In this case I needed to generate several BibTeX entries of the form:
author = {Doe, John},
title = {Lecture Note 1 - STAT10A},
month = {March},
year = {2018},
url = {https://statschool/~doe/stats10A/Lectures/Lecture01.pdf},
As it can be seen the lectures are numbered sequentially and change in the main
BibTeX `id`, the `title`, and the `url` field.
Specifically I needed to construct 30 such sequential entries for lectures
`1-30`. Rather than do this manually, I realized that this would be fun
scripting exercise with using the `tidyverse` packages `glue`, `purrr`, and
**Goal:** Create 30 such BibTeX entries and print to the console to
directly-copy paste to my BibTeX file.
### The `tidy` approach
First step is to write a function that takes a lecture number (integer) as an
input and then outputs a single BibTeX entry for that lecture.
```{r bbtex_01_01, eval=TRUE, echo=TRUE, cache=TRUE}
# Generate BibTeX entry for a single lecture number
get_lec_bibtex <- function(lec_num){
# Get the 2 character padded lecture number i.e. 1 -> "01"
lec_num_pad <- stringr::str_pad(string = lec_num, width = 2,
side = "left", pad = "0")
# Construct the BibTeX entry
out_bbtex_str <- glue::glue(
author = {Doe, John},
title = {Lecture Note <lec_num> - STAT10A},
month = {March},
year = {2018},
url = {https://www.hpg/~doe/st10A/lecs/lec<lec_num_pad>.pdf}}",
.open = "<",
.close = ">")
Note that by default `glue` allows you to substitute input text in between `{`
and `}` markers. However BibTeX entries *already have* literal default `{}`
tags that we need to include in our function output. Rather than escaping them
the `glue` package conveniently allows us to change the default opening and
closing markers `r emo::ji("hundred")`! We simply set these to be angle
brackets `< >` using the `.open` and `.close` options above.
<aside> __Note:__ Luckily we don't have _literal_ angle brackets in our BibTeX
output to deal with here</aside>
Let's just test this out quickly:
```{r bbtex_01_02, eval=TRUE, echo=TRUE, cache=TRUE}
lec_no <- 1
get_lec_bibtex(lec_num = lec_no)
Great - looks like it is working as required with the correct string padding in
the lecture number in the pdf filename!
<aside> **Note:** We used the `stringr` `str_pad` to convert `1` to `"01"`
### Apply to all lectures using `purrr`
Let's finish this by creating all the entries using `purrr`:
```{r bbtex_01_03, eval=TRUE, echo=TRUE, cache=TRUE}
lec_nums <- c(1, 30)
lec_nums %>%
purrr::map_chr(.x = ., .f = ~get_lec_bibtex(lec_num = .x)) %>%
cat(., sep = "\n\n")
Yay - this works as expected! We can now paste into BibTeX as required.
Note that we only created it for lectures 1 and 30 for easy scrolling. But for
all lectures we can just replace `c(1, 30)` with `1:30` in the above code.
## Conclusion
This post was for me to document and serve as a guide to automating a couple of
fun text-based tasks that I came across in my work (and social life!). Using
the `tidy` framework can be a fun way to solve these tasks (but certainly not
the only way in `R`). Have fun playing around with the above and please post in
the comments any questions/feedback you may have `r emo::ji("thumbsup")`.
Stay tuned for more blogposts solving more such tasks.
```{r, child=here::here("data", "rmds", "acknowledgment_preview_tidyfun_salil.Rmd")}
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