Merge pull request #791 from markfairbanks/pivot_wider-only-used-cols

`pivot_wider()`: Only use used cols

R/pivot_wider.R

@@ -128,18 +128,18 @@ pivot_wider.tidytable <- function(.df,
 
   formula <- glue("{lhs} ~ {rhs}")
 
-  dcast_call <- call2(
+  .dcast_df <- select(.df, any_of(c(id_cols, names_from, values_from)))
+
+  out <- eval_tidy(call2(
     "dcast",
-    quo(.df),
+    quo(.dcast_df),
     formula = formula,
     value.var = values_from,
     fun.aggregate = expr(!!values_fn),
     sep = names_sep,
     fill = values_fill,
     .ns = "data.table"
-  )
-
-  out <- eval_tidy(dcast_call)
+  ))
 
   out <- remove_key(out)
 
@@ -163,7 +163,8 @@ pivot_wider.tidytable <- function(.df,
                            .by = any_of(id_cols))
     out <- left_join(out, unused_df, by = id_cols)
   }
-  out
+
+  as_tidytable(out)
 }
 
 #' @export

tests/testthat/test-pivot_wider.R

@@ -242,6 +242,25 @@ test_that("correctly labels columns when `names_glue` is used, #579", {
 
 # unused -------------------------------------------------------------------
 
+test_that("only uses used columns when `unused_fn = NULL`, #698", {
+  df <- data.frame(
+    a   = LETTERS[1:2],
+    b   = LETTERS[3:4],
+    val = 1:2
+  )
+
+  res <- df %>%
+    pivot_wider(
+      id_cols = character(0),
+      names_from = a,
+      values_from = val
+    )
+
+  expect_named(res, c("A", "B"))
+  expect_equal(res$A, 1)
+  expect_equal(res$B, 2)
+})
+
 test_that("`unused_fn` can summarize unused columns (#990)", {
   df <- tidytable(
     id = c(1, 1, 2, 2),