Merge pull request #476 from arunsrinivasan/invalid_selfref

Fix for #475

NEWS.md

@@ -44,6 +44,7 @@
 * `do()` now displays the progress bar only when used in interactive prompts
   and not when knitting (#428, @jimhester).
 
+* `summarise` and `group_by` now retain over allocation when working with data.tables (#475, arunsrinivasan).
 
 # dplyr 0.2
 

R/grouped-dt.r

@@ -29,9 +29,9 @@ grouped_dt <- function(data, vars) {
 
   data <- copy(data)
   setkeyv(data, deparse_all(vars))
-
-  structure(data, vars = vars,
-    class = c("grouped_dt", "tbl_dt", "tbl", class(data)))
+  setattr(data, "vars", vars)
+  setattr(data, "class", c("grouped_dt", "tbl_dt", "tbl", class(data)))
+  data
 }
 
 #' @export
@@ -74,7 +74,7 @@ regroup.grouped_dt <- function(x, value) {
 
 #' @export
 ungroup.grouped_dt <- function(x) {
-  attr(x, "vars") <- NULL
-  class(x) <- setdiff(class(x), "grouped_dt")
+  setattr(x, "vars", NULL)
+  setattr(x, "class", setdiff(class(x), "grouped_dt"))
   x
 }

R/tbl-dt.r

@@ -18,8 +18,9 @@ tbl_dt <- function(data) {
   }
   if (is.grouped_dt(data)) return(ungroup(data))
 
-  data <- as.data.table(data)
-  structure(data, class = c("tbl_dt", "tbl", "data.table", "data.frame"))
+  if (is.data.table(data)) data <- copy(data) else data <- as.data.table(data)
+  setattr(data, "class", c("tbl_dt", "tbl", "data.table", "data.frame"))
+  data
 }
 
 #' @export

tests/testthat/test-group-by.r

@@ -160,3 +160,10 @@ test_that("group_by only creates one group for NA (#401)", {
   res <- data.frame(x=x,w=w) %>% group_by(x) %>% summarise(n=n())
   expect_equal(nrow(res), 11L) 
 })
+
+test_that("data.table invalid .selfref issue (#475)", {
+  dt <- data.table(x=1:5, y=6:10)
+  expect_that((dt %>% group_by(x))[, z := 2L], not(gives_warning()))
+  dt <- data.table(x=1:5, y=6:10)
+  expect_that((dt %>% group_by(x) %>% summarise(z = y^2))[, foo := 1L], not(gives_warning()))
+})