Adding keep_empty argument to list_c, list_cbind, and list_rbind.

NEWS.md

@@ -1,5 +1,6 @@
 # purrr (development version)
 
+* Added a new keep_empty argument to `list_c()`, `list_cbind()`, and `list_rbind()` which will keep empty elements as `NA` in the returned data frame (@SokolovAnatoliy, #1096).
 * `list_transpose()` now works with data.frames (@KimLopezGuell, #1109).
 * Added `imap_vec()` (#1084)
 * `list_transpose()` inspects all elements to determine the correct

R/list-combine.R

@@ -22,6 +22,9 @@
 #'   same size (i.e. number of rows).
 #' @param name_repair One of `"unique"`, `"universal"`, or `"check_unique"`.
 #'   See [vctrs::vec_as_names()] for the meaning of these options.
+#' @param keep_empty  An optional logical. If `FALSE` (the default), then
+#'   empty (`NULL`) elements are silently ignored; if `TRUE`, then empty
+#'   elements are preserved by converting to `NA`.
 #' @inheritParams rlang::args_dots_empty
 #' @export
 #' @examples
@@ -30,16 +33,21 @@
 #'
 #' x2 <- list(
 #'   a = data.frame(x = 1:2),
-#'   b = data.frame(y = "a")
+#'   b = data.frame(y = "a"),
+#'   c = NULL
 #' )
 #' list_rbind(x2)
 #' list_rbind(x2, names_to = "id")
+#' list_rbind(x2, names_to = "id", keep_empty = TRUE)
 #' list_rbind(unname(x2), names_to = "id")
-#'
 #' list_cbind(x2)
-list_c <- function(x, ..., ptype = NULL) {
+#' list_cbind(x2, keep_empty = TRUE)
+list_c <- function(x, ..., ptype = NULL, keep_empty = FALSE) {
   vec_check_list(x)
   check_dots_empty()
+  if (keep_empty) {
+    x <- convert_null_to_NA(x)
+  }
 
   # For `list_c()`, we don't expose `list_unchop()`'s `name_spec` arg,
   # and instead strip outer names to avoid collisions with inner names
@@ -58,19 +66,26 @@ list_cbind <- function(
     x,
     ...,
     name_repair = c("unique", "universal", "check_unique"),
-    size = NULL
+    size = NULL,
+    keep_empty = FALSE
   ) {
   check_list_of_data_frames(x)
   check_dots_empty()
+  if (keep_empty) {
+    x <- convert_null_to_NA(x)
+  }
 
   vec_cbind(!!!x, .name_repair = name_repair, .size = size, .error_call = current_env())
 }
 
 #' @export
 #' @rdname list_c
-list_rbind <- function(x, ..., names_to = rlang::zap(), ptype = NULL) {
+list_rbind <- function(x, ..., names_to = rlang::zap(), ptype = NULL, keep_empty = FALSE) {
   check_list_of_data_frames(x)
   check_dots_empty()
+  if (keep_empty) {
+    x <- convert_null_to_NA(x)
+  }
 
   vec_rbind(!!!x, .names_to = names_to, .ptype = ptype, .error_call = current_env())
 }
@@ -95,3 +110,9 @@ check_list_of_data_frames <- function(x, error_call = caller_env()) {
     call = error_call
   )
 }
+
+convert_null_to_NA <- function(x) {
+  is_null <- map_lgl(x, is.null)
+  x[is_null] <- list(NA)
+  x
+}

tests/testthat/_snaps/adverb-auto-browse.md

@@ -6,10 +6,3 @@
       Error in `auto_browse()`:
       ! `.f` must not be a primitive function.
 
----
-
-    Code
-      auto_browse(identity)(NULL)
-    Output
-      NULL
-

tests/testthat/_snaps/deprec-prepend.md

@@ -7,3 +7,27 @@
       `prepend()` was deprecated in purrr 1.0.0.
       i Please use append(after = 0) instead.
 
+# prepend throws error if before param is neither NULL nor between 1 and length(x)
+
+    Code
+      prepend(list(), 1, before = 1)
+    Condition
+      Error in `prepend()`:
+      ! is.null(before) || (before > 0 && before <= n) is not TRUE
+
+---
+
+    Code
+      x %>% prepend(4, before = 0)
+    Condition
+      Error in `prepend()`:
+      ! is.null(before) || (before > 0 && before <= n) is not TRUE
+
+---
+
+    Code
+      x %>% prepend(4, before = 4)
+    Condition
+      Error in `prepend()`:
+      ! is.null(before) || (before > 0 && before <= n) is not TRUE
+

tests/testthat/_snaps/deprec-utils.md

@@ -11,3 +11,35 @@
       Warning:
       `rbernoulli()` was deprecated in purrr 1.0.0.
 
+# rdunif fails if a and b are not unit length numbers
+
+    Code
+      rdunif(1000, 1, "a")
+    Condition
+      Error in `rdunif()`:
+      ! is.numeric(a) is not TRUE
+
+---
+
+    Code
+      rdunif(1000, 1, c(0.5, 0.2))
+    Condition
+      Error in `rdunif()`:
+      ! length(a) == 1 is not TRUE
+
+---
+
+    Code
+      rdunif(1000, FALSE, 2)
+    Condition
+      Error in `rdunif()`:
+      ! is.numeric(b) is not TRUE
+
+---
+
+    Code
+      rdunif(1000, c(2, 3), 2)
+    Condition
+      Error in `rdunif()`:
+      ! length(b) == 1 is not TRUE
+

tests/testthat/_snaps/deprec-when.md

@@ -7,3 +7,11 @@
       `when()` was deprecated in purrr 1.0.0.
       i Please use `if` instead.
 
+# error when named arguments have no matching conditions
+
+    Code
+      1:5 %>% when(a = sum(.) < 5 ~ 3)
+    Condition
+      Error in `when()`:
+      ! At least one matching condition is needed.
+

tests/testthat/_snaps/every-some-none.md

@@ -0,0 +1,16 @@
+# every() requires logical value
+
+    Code
+      every(list(1:3), identity)
+    Condition
+      Error in `every()`:
+      ! `.p()` must return a single `TRUE` or `FALSE`, not an integer vector.
+
+---
+
+    Code
+      every(list(function() NULL), identity)
+    Condition
+      Error in `every()`:
+      ! `.p()` must return a single `TRUE` or `FALSE`, not a function.
+

tests/testthat/_snaps/map-depth.md

@@ -20,6 +20,16 @@
       Error in `map_depth()`:
       ! Negative `.depth` (-5) must be greater than -4.
 
+# default doesn't recurse into data frames, but can customise
+
+    Code
+      map_depth(x, 2, class)
+    Condition
+      Error in `.fmap()`:
+      i In index: 1.
+      Caused by error in `map_depth()`:
+      ! List not deep enough
+
 # modify_depth modifies values at specified depth
 
     Code
@@ -42,6 +52,20 @@
       Error in `modify_depth()`:
       ! Negative `.depth` (-5) must be greater than -4.
 
+# vectorised operations on the recursive and atomic levels yield same results
+
+    Code
+      modify_depth(x, 5, `+`, 10L)
+    Condition
+      Error in `map()`:
+      i In index: 1.
+      Caused by error in `map()`:
+      i In index: 1.
+      Caused by error in `map()`:
+      i In index: 1.
+      Caused by error in `modify_depth()`:
+      ! List not deep enough
+
 # validates depth
 
     Code

tests/testthat/_snaps/pluck.md

@@ -277,3 +277,19 @@
       Error in `pluck_raw()`:
       ! Index 1 must have length 1, not 26.
 
+# pluck() dispatches on vector methods
+
+    Code
+      chuck(x, 1, 1)
+    Condition
+      Error in `chuck()`:
+      ! Length of S3 object must be a scalar integer.
+
+---
+
+    Code
+      chuck(x, 1, "b", 1)
+    Condition
+      Error in `chuck()`:
+      ! Index 2 is attempting to pluck from an unnamed vector using a string name.
+

tests/testthat/test-list-combine.R

@@ -70,6 +70,24 @@ test_that("NULLs are ignored", {
   expect_equal(list_cbind(list(df1, NULL, df2)), vec_cbind(df1, df2))
 })
 
+test_that("NULLs are converted to NA when keep_empty = TRUE", {
+  df1 <- data.frame(x = 1)
+  df2 <- data.frame(y = 1)
+
+  expect_equal(
+    list_c(list(1, NULL, 2), keep_empty = TRUE),
+    c(1, NA, 2)
+  )
+  expect_equal(
+    list_rbind(list(df1, NULL, df1), keep_empty = TRUE),
+    data.frame(x = c(1, NA, 1))
+  )
+  expect_equal(
+    list_cbind(list(df1, z = NULL, df2), keep_empty = TRUE),
+    data.frame(df1, z = NA, df2)
+  )
+})
+
 test_that("empty inputs return expected output", {
   expect_equal(list_c(list()), NULL)
   expect_equal(list_c(list(NULL)), NULL)