aoc

aoc provides usethis-style functions for Advent of Code puzzles. This package only downloads content from the Advent of Code site.

Installation

You can install the development version of aoc from GitHub with:

# install.packages("devtools")
remotes::install_github("tjmahr/aoc")

Preliminaries

aoc assumes that we are organizing our R code using an R package. Therefore, it requires a minimal package infrastructure in order to work. In RStudio, using

• File > New Project… > New Directory > R Package
• Setting the package name to adventofcode21 > Create Project

should create enough of an R package setup for aoc to work.

Alternatively, you can just use aoc::create_aoc(), specifying you package path as an argument in the function. This will create your aoc package for you and create a dev folder with scripts to help you start working on your aoc problems.

Functionality

aoc assumes that you are working inside an R package. By default, it assumes the package is named adventofcodeXX where XX are the last two digits of the year. For example, adventofcode20 would be the package for 2020.

From this setup, aoc will automate a number of tasks. use_day() is a usethis-style function to create placeholder files for each day.

use_day(day = 1) does the following tasks:

• on first run, creates R/data-solutions.R
  • a file for storing solutions
• creates R/day01.R
  • puts the puzzle description into a roxygen documentation block
  • creates placeholder functions for the solutions to day 1
• creates tests/testthat/test-day01.R
  • a unit test for day (useful for the example in the puzzle description) in tests/testthat/test-day01.R
• creates inst/input01.txt
  • a file to hold the input for day 1
• creates inst/run-day01.R
  • a file to contain the solution for day 1

aoc::use_day(1, year = 2020)
#> ✔ Writing 'R/data-solutions.R'
#> • Modify 'R/data-solutions.R'
#> downloading puzzle html using .aoccookie
#> Executing: pandoc -t markdown -o 
#> "C:\Users\trist\AppData\Local\Temp\RtmpK8sv2r\file228c54056ded.markdown" 
#> "C:\Users\trist\AppData\Local\Temp\RtmpK8sv2r\file228c54056ded.html"
#> ✔ Writing 'R/day01.R'
#> ● Write your solution code here
#> ● Once you unlock Part Two, update the Roxygen block with the description
#> ✔ Writing 'inst/input01.txt'
#> ● Copy your problem input into this file
#> ✔ Writing 'tests/testthat/test-day01.R'
#> • Edit 'tests/testthat/test-day01.R'
#> ● Write unit tests using the examples from the problem description
#> ✔ Writing 'inst/run-day01.R'
#> ● Run your solution on the input here. Once it works, update R/data-solutions.R

R/data-solutions.R is where we store our solutions:

#' Advent of Code 2020 solutions
#' @export
aoc_solutions <- list(
  day01a = NA,
  day01b = NA,
  day02a = NA,
  day02b = NA,
  day03a = NA,
  day03b = NA,
  day04a = NA,
  day04b = NA,
  day05a = NA,
  day05b = NA,
  day06a = NA,
  day06b = NA,
  day07a = NA,
  day07b = NA,
  day08a = NA,
  day08b = NA,
  day09a = NA,
[... truncated ...]

inst/input01.txt is an empty file for our input data. We have to paste in our puzzle input here.

The R script for R/day01.R provides the puzzle description for part 1, function stubs for part 1 f01a() and part 2 f01b(). I also like to make the example data into a function for unit tests or code examples, so there is a stub for example_data_01().

#' Day 01: Report Repair
#'
#' [Report Repair](https://adventofcode.com/2020/day/1)
#'
#' @name day01
#' @rdname day01
#' @details
#'
#' **Part One**
#'
#' After saving Christmas [five years in a row](/events), you\'ve decided
#' to take a vacation at a nice resort on a tropical island.
#' [Surely]{title="WHAT COULD GO WRONG"}, Christmas will go on without you.
#' 
#' The tropical island has its own currency and is entirely cash-only. The
#' gold coins used there have a little picture of a starfish; the locals
#' just call them *stars*. None of the currency exchanges seem to have
#' heard of them, but somehow, you\'ll need to find fifty of these coins by
#' the time you arrive so you can pay the deposit on your room.
#' 
#' To save your vacation, you need to get all *fifty stars* by December
#' 25th.
#' 
#' Collect stars by solving puzzles. Two puzzles will be made available on
#' each day in the Advent calendar; the second puzzle is unlocked when you
#' complete the first. Each puzzle grants *one star*. Good luck!
#' 
#' Before you leave, the Elves in accounting just need you to fix your
#' *expense report* (your puzzle input); apparently, something isn\'t quite
#' adding up.
#' 
#' Specifically, they need you to *find the two entries that sum to `2020`*
#' and then multiply those two numbers together.
#' 
#' For example, suppose your expense report contained the following:
#' 
#'     1721
#'     979
#'     366
#'     299
#'     675
#'     1456
#' 
#' In this list, the two entries that sum to `2020` are `1721` and `299`.
#' Multiplying them together produces `1721 * 299 = 514579`, so the correct
#' answer is *`514579`*.
#' 
#' Of course, your expense report is much larger. *Find the two entries
#' that sum to `2020`; what do you get if you multiply them together?*
#'
#' **Part Two**
#'
#' *(Use have to manually add this yourself.)*
#'
#' *(Try using `convert_clipboard_html_to_roxygen_md()`)*
#'
#' @param x some data
#' @return For Part One, `f01a(x)` returns .... For Part Two,
#'   `f01b(x)` returns ....
#' @export
#' @examples
#' f01a(example_data_01())
#' f01b()
f01a <- function(x) {

}


#' @rdname day01
#' @export
f01b <- function(x) {

}


f01_helper <- function(x) {

}


#' @param example Which example data to use (by position or name). Defaults to
#'   1.
#' @rdname day01
#' @export
example_data_01 <- function(example = 1) {
  l <- list(
    a = c(

    )
  )
  l[[example]]
}

tests/testthat/test-day01.R is a placeholder for file unit tests. It’s a good place work through the examples in the puzzle description.

test_that("multiplication works", {
  expect_equal(2 * 2, 4)
})

Once we have developed a solution for the example input, we can test our official input by running the code in inst/run-day01.R. The final two lines provide code to validate the solutions that we store in R/data-solutions.R.

library(adventofcode20)
x <- readLines("./inst/input01.txt")

p1 <- f01a(x)
p2 <- f01b(x)

stopifnot(p1 == aoc_solutions$day01a)
stopifnot(p2 == aoc_solutions$day01b)

Default values for use_day()

We can tell aoc which year to use by using options().

options(aoc.year = 2017)
aoc::use_day(3)
#> Executing: pandoc -t markdown -o "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file49483da20fa.markdown" "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file49483da20fa.html"
#> ✔ Writing 'R/day03.R'
#> ● Write your solution code here
#> ● Once you unlock Part Two, update the Roxygen block with the description
#> ✔ Writing 'inst/input03.txt'
#> ● Copy your problem input into this file
#> ✔ Writing 'tests/testthat/test-day03.R'
#> • Edit 'tests/testthat/test-day03.R'
#> ● Write unit tests using the examples from the problem description
#> ✔ Writing 'inst/run-day03.R'
#> ● Run your solution on the input here. Once it works, update R/data-solutions.R

If we look at the first lines of R/day03.R, we can see the correct URL used.

#' Day 03: Spiral Memory
#'
#' [Spiral Memory](https://adventofcode.com/2017/day/3)
#'
#' @name day03
#' @rdname day03
#' @details
#'
#' **Part One**
#'
[... truncated ...]

We can also tell aoc which package name to use for our project using options().

options(aoc.package = "awesomeadvent2017")
aoc::use_day(4)
#> Executing: pandoc -t markdown -o "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file494890a25ab.markdown" "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file494890a25ab.html"
#> ✔ Writing 'R/day04.R'
#> ● Write your solution code here
#> ● Once you unlock Part Two, update the Roxygen block with the description
#> ✔ Writing 'inst/input04.txt'
#> ● Copy your problem input into this file
#> ✔ Writing 'tests/testthat/test-day04.R'
#> • Edit 'tests/testthat/test-day04.R'
#> ● Write unit tests using the examples from the problem description
#> ✔ Writing 'inst/run-day04.R'
#> ● Run your solution on the input here. Once it works, update R/data-solutions.R

And here the correct name appears in the library() call.

library(awesomeadvent2017)
x <- readLines("./inst/input04.txt")

p1 <- f04a(x)
p2 <- f04b(x)

stopifnot(p1 == aoc_solutions$day04a)
stopifnot(p2 == aoc_solutions$day04b)

We can set these permanently for an Advent of Code package by editing the package’s .Rprofile:

usethis::edit_r_profile(scope = "project")
# add in things like `options(aoc.year = 2017)`

Advanced: Using a user cookie

If you know how to retrieve the cookie for your Advent of Code user, you can use this cookie to download your puzzle input. Store the cookie in file named .aoccookie. Then use_day() will automatically use this cookie when downloading puzzle input.

For these demos, I hid my cookie by renaming the file. If I unrename the file and download the day 7 files, I can preview the lines of the input file.

file.rename(".xaoccookie", ".aoccookie")
#> [1] TRUE

aoc::use_day(7)
#> downloading puzzle html using .aoccookie
#> Executing: pandoc -t markdown -o "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file49485df03093.markdown" "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file49485df03093.html"
#> ✔ Writing 'R/day07.R'
#> ● Write your solution code here
#> ● Once you unlock Part Two, update the Roxygen block with the description
#> downloading puzzle input using .aoccookie
#> ✔ Writing 'inst/input07.txt'
#> ● Copy your problem input into this file
#> ✔ Writing 'tests/testthat/test-day07.R'
#> • Edit 'tests/testthat/test-day07.R'
#> ● Write unit tests using the examples from the problem description
#> ✔ Writing 'inst/run-day07.R'
#> ● Run your solution on the input here. Once it works, update R/data-solutions.R

# this is a function i defined in a hidden code block 🤫
preview_lines("inst/input07.txt")
#> uglvj (99) -> ymfjt, gkpgf
#> vvwrg (51)
#> qrpgt (5)
#> qhqbqj (55)
#> taxdaf (23)
#> zbbdyc (81)
#> xhymdo (185) -> errip, lsppdni, mxukll
#> qlrcubm (81)
#> ukgzz (7)
#> ubvvr (288) -> hrpzu, msjeeks, ozizlok
#> [... truncated ...]

The other advantage of a user cookie is that after solving part 1 of a day, we can download part 2 as a roxygen2 block. By default, this block is copied to the clipboard, but for this demo, I have to disable it.

aoc::download_part2_to_roxygen_md(day = 7, clip = FALSE)
downloading puzzle html using .aoccookie
Executing: pandoc -t markdown -o "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file494853b95982.markdown" "C:\Users\trist\AppData\Local\Temp\RtmpCYEhnm\file494853b95982.html"
#' **Part Two**
#' The programs explain the situation: they can\'t get down. Rather, they
#' *could* get down, if they weren\'t expending all of their energy trying
#' to keep the tower balanced. Apparently, one program has the *wrong
#' weight*, and until it\'s fixed, they\'re stuck here.
#' 
#' For any program holding a disc, each program standing on that disc forms
#' a sub-tower. Each of those sub-towers are supposed to be the same
#' weight, or the disc itself isn\'t balanced. The weight of a tower is the
#' sum of the weights of the programs in that tower.
#' 
#' In the example above, this means that for `ugml`\'s disc to be balanced,
#' `gyxo`, `ebii`, and `jptl` must all have the same weight, and they do:
#' `61`.
#' 
#' However, for `tknk` to be balanced, each of the programs standing on its
#' disc *and all programs above it* must each match. This means that the
#' following sums must all be the same:
#' 
#' -   `ugml` + (`gyxo` + `ebii` + `jptl`) = 68 + (61 + 61 + 61) = 251
#' -   `padx` + (`pbga` + `havc` + `qoyq`) = 45 + (66 + 66 + 66) = 243
#' -   `fwft` + (`ktlj` + `cntj` + `xhth`) = 72 + (57 + 57 + 57) = 243
#' 
#' As you can see, `tknk`\'s disc is unbalanced: `ugml`\'s stack is heavier
#' than the other two. Even though the nodes above `ugml` are balanced,
#' `ugml` itself is too heavy: it needs to be `8` units lighter for its
#' stack to weigh `243` and keep the towers balanced. If this change were
#' made, its weight would be `60`.
#' 
#' Given that exactly one program is the wrong weight, *what would its
#' weight need to be* to balance the entire tower? 

Credit

Thanks to {golem} for their implementation of dev files to support package development. aoc::create_aoc() is inspired by and based on golem::create_golem().

Hex icon created using the hexmake app from ColinFay.

Star icons created by Freepik - Flaticon