Fix colwise issue when predicate returns a FALSE vector

Closes tidyverse#1989

NEWS.md

@@ -1,5 +1,8 @@
 # dplyr 0.5.0.9000
 
+* Fix issue with `mutate_if()` and `summarise_if()` when a predicate
+  function returns a vector of `FALSE` (#1989, #2009).
+
 # dplyr 0.5.0
 
 ## Breaking changes

R/colwise.R

@@ -70,15 +70,17 @@
 #' @export
 summarise_all <- function(.tbl, .funs, ...) {
   funs <- as.fun_list(.funs, .env = parent.frame(), ...)
-  vars <- colwise_(.tbl, funs, list())
+  cols <- lazyeval::lazy_dots(everything())
+  vars <- colwise_(.tbl, funs, cols)
   summarise_(.tbl, .dots = vars)
 }
 
 #' @rdname summarise_all
 #' @export
 mutate_all <- function(.tbl, .funs, ...) {
   funs <- as.fun_list(.funs, .env = parent.frame(), ...)
-  vars <- colwise_(.tbl, funs, list())
+  cols <- lazyeval::lazy_dots(everything())
+  vars <- colwise_(.tbl, funs, cols)
   mutate_(.tbl, .dots = vars)
 }
 
@@ -192,9 +194,6 @@ colwise_ <- function(tbl, calls, vars) {
   named_calls <- attr(calls, "has_names")
   named_vars <- any(has_names(vars))
 
-  if (length(vars) == 0) {
-    vars <- lazyeval::lazy_dots(everything())
-  }
   vars <- select_vars_(tbl_vars(tbl), vars, exclude = as.character(groups(tbl)))
 
   out <- vector("list", length(vars) * length(calls))
@@ -248,6 +247,9 @@ summarise_each <- function(tbl, funs, ...) {
 #' @export
 #' @rdname summarise_each
 summarise_each_ <- function(tbl, funs, vars) {
+  if (length(vars) == 0) {
+    vars <- lazyeval::lazy_dots(everything())
+  }
   if (is.character(funs)) {
     funs <- funs_(funs)
   }
@@ -277,6 +279,9 @@ mutate_each <- function(tbl, funs, ...) {
 #' @export
 #' @rdname summarise_each
 mutate_each_ <- function(tbl, funs, vars) {
+  if (length(vars) == 0) {
+    vars <- lazyeval::lazy_dots(everything())
+  }
   vars <- colwise_(tbl, funs, vars)
   mutate_(tbl, .dots = vars)
 }

tests/testthat/test-colwise.R

@@ -74,13 +74,21 @@ test_that("sql sources fail with bare functions", {
   expect_error(memdb_frame(x = 1) %>% mutate_all(mean) %>% collect())
 })
 
+test_that("empty selection does not select everything (#2009, #1989)", {
+  expect_equal(mtcars, mutate_if(mtcars, is.factor, as.character))
+})
+
 
 # Deprecated ---------------------------------------------------------
 
-test_that("summarise_each() and summarise_all() agree", {
+test_that("_each() and _all() families agree", {
   df <- data.frame(x = 1:3, y = 1:3)
 
   expect_equal(summarise_each(df, funs(mean)), summarise_all(df, mean))
   expect_equal(summarise_each(df, funs(mean), x:y), summarise_at(df, vars(x:y), mean))
   expect_equal(summarise_each(df, funs(mean), z = y), summarise_at(df, vars(z = y), mean))
+
+  expect_equal(mutate_each(df, funs(mean)), mutate_all(df, mean))
+  expect_equal(mutate_each(df, funs(mean), x:y), mutate_at(df, vars(x:y), mean))
+  expect_equal(mutate_each(df, funs(mean), z = y), mutate_at(df, vars(z = y), mean))
 })