Implement union_all.

Fixes tidyverse#1045

NAMESPACE

@@ -300,6 +300,9 @@ S3method(ungroup,tbl_sql)
 S3method(union,data.frame)
 S3method(union,default)
 S3method(union,tbl_sql)
+S3method(union_all,data.frame)
+S3method(union_all,default)
+S3method(union_all,tbl_sql)
 S3method(unique,sql)
 S3method(update,tbl_sql)
 export("%>%")
@@ -510,6 +513,7 @@ export(trunc_mat)
 export(type_sum)
 export(ungroup)
 export(union)
+export(union_all)
 export(with_order)
 import(DBI)
 import(assertthat)

NEWS.md

@@ -1,5 +1,8 @@
 # dplyr 0.4.3.9000
 
+* New `union_all()` method. Maps to `UNION ALL` for SQL sources, `bind_rows()`
+  for data frames/tbl\_dfs, and `combine()` for vectors (#1045).
+
 * `src_sqlite()` throws errors if you try and use it with window functions 
   (#907).
 

R/dataframe.R

@@ -424,6 +424,9 @@ intersect.data.frame <- function(x, y, ...) intersect_data_frame(x, y)
 #' @export
 union.data.frame <-     function(x, y, ...) union_data_frame(x, y)
 
+#' @export
+union_all.data.frame <- function(x, y, ...) bind_rows(x, y)
+
 #' @export
 setdiff.data.frame <-   function(x, y, ...) setdiff_data_frame(x, y)
 

R/sets.r

@@ -17,6 +17,7 @@
 #' setdiff(first, second)
 #' setdiff(second, first)
 #'
+#' union_all(first, second)
 #' setequal(mtcars, mtcars[32:1, ])
 NULL
 
@@ -28,6 +29,9 @@ intersect <- function(x, y, ...) UseMethod("intersect")
 union <- function(x, y, ...) UseMethod("union")
 #' @rdname setops
 #' @export
+union_all <- function(x, y, ...) UseMethod("union_all")
+#' @rdname setops
+#' @export
 setdiff <- function(x, y, ...) UseMethod("setdiff")
 #' @rdname setops
 #' @export
@@ -38,6 +42,8 @@ intersect.default <- function(x, y, ...) base::intersect(x, y, ...)
 #' @export
 union.default <-     function(x, y, ...) base::union(x, y, ...)
 #' @export
+union_all.default <- function(x, y, ...) combine(x, y, ...)
+#' @export
 setdiff.default <-   function(x, y, ...) base::setdiff(x, y, ...)
 #' @export
 setequal.default <-  function(x, y, ...) base::setequal(x, y, ...)

R/tbl-sql.r

@@ -182,6 +182,12 @@ union.tbl_sql <- function(x, y, copy = FALSE, ...) {
   update(tbl(x$src, sql), group_by = groups(x))
 }
 #' @export
+union_all.tbl_sql <- function(x, y, copy = FALSE, ...) {
+  y <- auto_copy(x, y, copy)
+  sql <- sql_set_op(x$src$con, x, y, "UNION ALL")
+  update(tbl(x$src, sql), group_by = groups(x))
+}
+#' @export
 setdiff.tbl_sql <- function(x, y, copy = FALSE, ...) {
   y <- auto_copy(x, y, copy)
   sql <- sql_set_op(x$src$con, x, y, "EXCEPT")

tests/testthat/test-union-all.R

@@ -0,0 +1,22 @@
+context("union_all")
+
+test_that("union all on vectors concatenates", {
+  expect_equal(union_all(1:3, 4:6), 1:6)
+})
+
+test_that("union all on data frames calls bind rows", {
+  df1 <- data_frame(x = 1:2)
+  df2 <- data_frame(y = 1:2)
+
+  expect_equal(union_all(df1, df2), bind_rows(df1, df2))
+})
+
+test_that("union on database uses UNION ALL", {
+  db <- src_sqlite(":memory:", TRUE)
+
+  df1 <- copy_to(db, data_frame(x = 1:2), "df1")
+  df2 <- copy_to(db, data_frame(x = 1:2), "df2")
+
+  res <- collect(union_all(df1, df2))
+  expect_equal(res$x, rep(1:2, 2))
+})