Github user actuaryzhang commented on a diff in the pull request:
https://github.com/apache/spark/pull/17159#discussion_r104335939
--- Diff: R/pkg/R/DataFrame.R ---
@@ -2685,7 +2686,8 @@ setMethod("unionAll",
#' Union two or more SparkDataFrames
#'
-#' Union two or more SparkDataFrames. This is equivalent to \code{UNION
ALL} in SQL.
+#' Union two or more SparkDataFrames by row. In constrast to \link{union},
this method
+#' requires that the input SparkDataFrames have the same column names.
--- End diff --
Thanks. Updated doc. R's `rbind` seems to do type conversion similarly to
`union`:
```
df <- data.frame(name = c("Michael", "Andy", "Justin"), age = c(1, 30, 19))
df2 <- df
df2$age <- as.character(df2$age)
rbind(df, df2)
name age
1 Michael 1
2 Andy 30
3 Justin 19
4 Michael 1
5 Andy 30
6 Justin 19
str(rbind(df, df2))
'data.frame': 6 obs. of 2 variables:
$ name: Factor w/ 3 levels "Andy","Justin",..: 3 1 2 3 1 2
$ age : chr "1" "30" "19" "1" ...
```
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