Merge pull request #23 from krlmlr/feature/22-as_data_frame.table

- New `as_data_frame.table()` with argument `n` to control name of count column (#22, #23).

NAMESPACE

@@ -9,6 +9,7 @@ S3method(as_data_frame,"NULL")
 S3method(as_data_frame,data.frame)
 S3method(as_data_frame,list)
 S3method(as_data_frame,matrix)
+S3method(as_data_frame,table)
 S3method(as_data_frame,tbl_df)
 S3method(format_v,character)
 S3method(format_v,default)

R/dataframe.R

@@ -103,7 +103,7 @@ lst_ <- function(xs) {
 #' with more efficient methods for matrices and data frames.
 #'
 #' This is an S3 generic. tibble includes methods for data frames (adds tbl_df
-#' classes), tbl_dfs (trivial!), lists, and matrices.
+#' classes), tbl_dfs (trivial!), lists, matrices, and tables.
 #'
 #' @param x A list. Each element of the list must have the same length.
 #' @param ... Other arguments passed on to individual methods.
@@ -188,6 +188,13 @@ as_data_frame.matrix <- function(x, ...) {
   x
 }
 
+#' @export
+#' @param n Name for count column, default: \code{"n"}.
+#' @rdname as_data_frame
+as_data_frame.table <- function(x, n = "n", ...) {
+  as_data_frame(as.data.frame(x, responseName = n, stringsAsFactors = FALSE))
+}
+
 #' @export
 #' @rdname as_data_frame
 as_data_frame.NULL <- function(x, ...) {

tests/testthat/test-data_frame.R

@@ -109,6 +109,18 @@ test_that("NULL makes 0 x 0 tbl_df", {
   expect_equal(dim(nnnull), c(0L, 0L))
 })
 
+
+test_that("Can convert tables to data frame", {
+  mtcars_table <- xtabs(mtcars, formula = ~vs+am+cyl)
+
+  mtcars_tbl <- as_data_frame(mtcars_table)
+  expect_equal(names(mtcars_tbl), c(names(dimnames(mtcars_table)), "n"))
+
+  mtcars_tbl <- as_data_frame(mtcars_table, "Freq")
+  expect_equal(names(mtcars_tbl), c(names(dimnames(mtcars_table)), "Freq"))
+})
+
+
 # Validation --------------------------------------------------------------
 
 test_that("2d object isn't a valid column", {