Add several functions (#9)

* Use Roxygen to generate docs.

* Add latin constraint testing functions.

* Add remove_both function.

DESCRIPTION

@@ -8,4 +8,7 @@ Description: Room squares in R.
 License: MIT + file LICENSE
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.0.0
+RoxygenNote: 7.3.1
+Imports:
+  purrr,
+  tidyr

R/latin.R

@@ -0,0 +1,43 @@
+#' Does a row satisfy the latin constraint?
+#'
+#' @param R A Room square
+#' @param i A row index
+#'
+#' @return True if and only if row i of R satisfies the latin constraint.
+is_row_latin_i <- function(R, i) {
+  R <- R |> tidyr::pivot_longer(first:second)
+  u <- R[R$row == i, "value"]$value
+  u <- u[!is.na(u)]
+  length(u) == length(unique(u))
+}
+
+#' Does a column satisfy the latin constraint?
+#'
+#' @param R A Room square
+#' @param i A column index
+#'
+#' @return True if and only if column i of R satisfies the latin constraint.
+is_col_latin_i <- function(R, i) {
+  R <- R |> tidyr::pivot_longer(first:second)
+  u <- R[R$col == i, "value"]$value
+  u <- u[!is.na(u)]
+  length(u) == length(unique(u))
+}
+
+#' Is a Room square row latin?
+#'
+#' @param R A Room square
+#'
+#' @return True if and only if R is row latin.
+is_row_latin <- function(R) {
+  all(purrr::map_lgl(1:max(R$row), is_row_latin_i, R = R))
+}
+
+#' Is A Room square column latin?
+#'
+#' @param R A Room square
+#'
+#' @return True if and only if R is column latin.
+is_col_latin <- function(R) {
+  all(purrr::map_lgl(1:max(R$col), is_col_latin_i, R = R))
+}

R/remove-both.R

@@ -0,0 +1,17 @@
+#' Remove both elements of a pair from a list
+#'
+#' @param X A list
+#' @param p A pair
+#'
+#' @return The list X with both elements of p removed (if they exist).
+remove_both <- function(X, p) {
+  m1 <- match(p[1], X)
+  if(!is.na(m1)) {
+    X <- X[-m1]
+  }
+  m2 <- match(p[2], X)
+  if(!is.na(m2)) {
+    X <- X[-m2]
+  }
+  return(X)
+}

wallis.Rproj

@@ -15,3 +15,4 @@ LaTeX: pdfLaTeX
 BuildType: Package
 PackageUseDevtools: Yes
 PackageInstallArgs: --no-multiarch --with-keep.source
+PackageRoxygenize: rd,collate,namespace