new rownames arg, closes #288, closes #289

- `as_tibble()` gains `rownames` argument (#288, #289).

R/as_tibble.R

@@ -19,6 +19,10 @@
 #'   want to suppress this when you know that you already have a valid data
 #'   frame and you want to save some time, or to explicitly enable it
 #'   if you have a tibble that you want to re-check.
+#' @param rownames If `NULL`, remove row names (default for matrices, may become
+#'   default for data frames in the future). If `NA`, keep row names (current
+#'   default for data frames). Otherwise, the name of the new column that will
+#'   contain the existing row names.
 #' @export
 #' @examples
 #' l <- list(x = 1:500, y = runif(500), z = 500:1)
@@ -57,15 +61,22 @@ as_tibble <- function(x, ...) {
 
 #' @export
 #' @rdname as_tibble
-as_tibble.tbl_df <- function(x, ..., validate = FALSE) {
+as_tibble.tbl_df <- function(x, ..., validate = FALSE, rownames = NULL) {
   if (validate) return(NextMethod())
   x
 }
 
 #' @export
 #' @rdname as_tibble
-as_tibble.data.frame <- function(x, validate = TRUE, ...) {
-  list_to_tibble(x, validate, raw_rownames(x))
+as_tibble.data.frame <- function(x, validate = TRUE, ..., rownames = NA) {
+  result <- list_to_tibble(x, validate, raw_rownames(x))
+  if (is.null(rownames)) {
+    remove_rownames(result)
+  } else if (is.na(rownames)) {
+    result
+  } else {
+    rownames_to_column(result, var = rownames)
+  }
 }
 
 #' @export
@@ -99,8 +110,8 @@ list_to_tibble <- function(x, validate, rownames = NULL) {
 
 #' @export
 #' @rdname as_tibble
-as_tibble.matrix <- function(x, ...) {
-  matrixToDataFrame(x)
+as_tibble.matrix <- function(x, ..., rownames = NULL) {
+  as_tibble(matrixToDataFrame(x), ..., rownames = rownames)
 }
 
 #' @export

src/matrixToDataFrame.c

@@ -246,10 +246,8 @@ static SEXP get_class(void)
 {
   SEXP cls;
 
-  PROTECT(cls = Rf_allocVector(STRSXP, 3));
-  SET_STRING_ELT(cls, 0, Rf_mkChar("tbl_df"));
-  SET_STRING_ELT(cls, 1, Rf_mkChar("tbl"));
-  SET_STRING_ELT(cls, 2, Rf_mkChar("data.frame"));
+  PROTECT(cls = Rf_allocVector(STRSXP, 1));
+  SET_STRING_ELT(cls, 0, Rf_mkChar("data.frame"));
   UNPROTECT(1);
 
   return cls;

tests/testthat/test-data-frame.R

@@ -228,6 +228,21 @@ test_that("as_tibble() can validate (#278)", {
 })
 
 
+test_that("as_tibble() can convert row names", {
+  df <- data.frame(a = 1:3, b = 2:4, row.names = letters[5:7])
+  expect_identical(
+    as_tibble(df, rownames = NULL),
+    tibble(a = 1:3, b = 2:4)
+  )
+  expect_identical(
+    as_tibble(df, rownames = "id"),
+    tibble(id = letters[5:7], a = 1:3, b = 2:4)
+  )
+  expect_identical(rownames(as_tibble(df)), rownames(df))
+  expect_identical(unclass(as_tibble(df)), unclass(df))
+})
+
+
 test_that("as_data_frame is an alias of as_tibble", {
   expect_identical(as_data_frame(NULL), as_tibble(NULL))
 })

tests/testthat/test-matrix.R

@@ -80,11 +80,26 @@ test_that("forwarding to as.data.frame() for ts objects (#184)", {
 })
 
 
-test_that("converting from matrix keeps row names if argument has them", {
-    x <- matrix(1:30, 6, 5, dimnames = list(letters[1:6], LETTERS[1:5]))
-    df <- data.frame(A = 1:6, B = 7:12, C = 13:18, D = 19:24, E = 25:30,
-                     row.names = letters[1:6])
-    out <- as_tibble(x)
-    expect_identical(rownames(out), rownames(x))
-    expect_identical(out, as_tibble(df))
+test_that("converting from matrix removes row names by default", {
+  x <- matrix(1:30, 6, 5, dimnames = list(letters[1:6], LETTERS[1:5]))
+  df <- data.frame(A = 1:6, B = 7:12, C = 13:18, D = 19:24, E = 25:30)
+  out <- as_tibble(x)
+  expect_false(has_rownames(out))
+  expect_identical(out, as_tibble(df))
+})
+
+test_that("converting from matrix keeps row names if argument has them, with rownames = NA", {
+  x <- matrix(1:30, 6, 5, dimnames = list(letters[1:6], LETTERS[1:5]))
+  df <- data.frame(A = 1:6, B = 7:12, C = 13:18, D = 19:24, E = 25:30,
+                   row.names = letters[1:6])
+  out <- as_tibble(x, rownames = NA)
+  expect_identical(rownames(out), rownames(x))
+  expect_identical(out, as_tibble(df))
+})
+
+test_that("converting from matrix supports storing row names in a column", {
+  x <- matrix(1:30, 6, 5, dimnames = list(letters[1:6], LETTERS[1:5]))
+  df <- tibble(id = letters[1:6], A = 1:6, B = 7:12, C = 13:18, D = 19:24, E = 25:30)
+  out <- as_tibble(x, rownames = "id")
+  expect_identical(out, df)
 })