From 0881bf4c0c0cd7bd1102a50273ce2ca73fa91aa1 Mon Sep 17 00:00:00 2001
From: EllaKaye <ella.kaye@gmail.com>
Date: Mon, 1 Jan 2024 11:05:32 +0000
Subject: [PATCH] Add `lines_to_matrix()` (closes #4)

---
 NAMESPACE                             |  1 +
 NEWS.md                               |  1 +
 R/read.R                              |  2 +-
 R/wrangle-helpers.R                   | 14 ++++++++++++++
 _pkgdown.yml                          |  2 ++
 man/lines_to_matrix.Rd                | 22 ++++++++++++++++++++++
 tests/testthat/test-wrangle-helpers.R |  8 ++++++++
 7 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 R/wrangle-helpers.R
 create mode 100644 man/lines_to_matrix.Rd
 create mode 100644 tests/testthat/test-wrangle-helpers.R

diff --git a/NAMESPACE b/NAMESPACE
index b445c8d..802d5a1 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -16,3 +16,4 @@ export(aoc_url_input)
 export(extract_numbers)
 export(gcd)
 export(lcm)
+export(lines_to_matrix)
diff --git a/NEWS.md b/NEWS.md
index 0a6d1be..4192968 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -5,3 +5,4 @@
 * Add user agent to `aoc_get_input()`
 * Add `extract_numbers()` to extract all numbers from a string
 * Add `gcd()` and `lcm()` for finding greatest common divisor and lowest common multiple
+* Add `lines_to_matrix()`
diff --git a/R/read.R b/R/read.R
index 072b3cb..9e71018 100644
--- a/R/read.R
+++ b/R/read.R
@@ -117,7 +117,7 @@ aoc_input_matrix <- function(day, year = NULL, mode = c("character", "numeric"),
 
 	input <- readr::read_lines(aoc_input_path(day, year))
 
-	input <- matrix(unlist(strsplit(input, split = split)), nrow = length(input), byrow = TRUE)
+	input <- strsplit(input, split) |> do.call(rbind, args = _)
 
 	if (mode == "numeric") {
 		input <- apply(input, 2, as.numeric)
diff --git a/R/wrangle-helpers.R b/R/wrangle-helpers.R
new file mode 100644
index 0000000..f5b5288
--- /dev/null
+++ b/R/wrangle-helpers.R
@@ -0,0 +1,14 @@
+#' Convert vectors to a matrix
+#'
+#' For the default split of `"`, assumes that each element of `lines` has the same number of characters.
+#'
+#' @param lines a vector
+#' @param split character. The string to split the input on. Default is `""`, i.e. one character per column
+#'
+#' @return A matrix where the number of rows is the length of `lines` and, for a split on `"`, the number of columns is the same as the number of characters in each element of `lines`.
+#' @export
+#'
+#' @examples lines_to_matrix(c("#.#.", "..#.", "##.."))
+lines_to_matrix <- function(lines, split = "") {
+	strsplit(lines, split) |> do.call(rbind, args = _)
+}
diff --git a/_pkgdown.yml b/_pkgdown.yml
index 65594bf..d78bdf4 100644
--- a/_pkgdown.yml
+++ b/_pkgdown.yml
@@ -33,6 +33,8 @@ reference:
     - aoc_input_data_frame
     - aoc_input_matrix
     - aoc_input_vector
+  - title: "Helpers for wrangling data"
+    - lines_to_matrix
   - title: "Helper functions for working with strings"
     contents:
     - extract_numbers
diff --git a/man/lines_to_matrix.Rd b/man/lines_to_matrix.Rd
new file mode 100644
index 0000000..041f6b6
--- /dev/null
+++ b/man/lines_to_matrix.Rd
@@ -0,0 +1,22 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/wrangle-helpers.R
+\name{lines_to_matrix}
+\alias{lines_to_matrix}
+\title{Convert vectors to a matrix}
+\usage{
+lines_to_matrix(lines, split = "")
+}
+\arguments{
+\item{lines}{a vector}
+
+\item{split}{character. The string to split the input on. Default is \code{""}, i.e. one character per column}
+}
+\value{
+A matrix where the number of rows is the length of \code{lines} and, for a split on \verb{"}, the number of columns is the same as the number of characters in each element of \code{lines}.
+}
+\description{
+For the default split of \verb{"}, assumes that each element of \code{lines} has the same number of characters.
+}
+\examples{
+lines_to_matrix(c("#.#.", "..#.", "##.."))
+}
diff --git a/tests/testthat/test-wrangle-helpers.R b/tests/testthat/test-wrangle-helpers.R
new file mode 100644
index 0000000..50e0971
--- /dev/null
+++ b/tests/testthat/test-wrangle-helpers.R
@@ -0,0 +1,8 @@
+# write test for lines_to_matrix
+test_that("lines_to_matrix works", {
+	expect_equal(lines_to_matrix(c("#.#.", "..#.", "##..")),
+							 matrix(c("#", ".", "#", ".",
+							 				 ".", ".", "#", ".",
+							 				 "#", "#", ".", "."
+							 				 ), byrow = TRUE, nrow = 3))
+})