Github user shivaram commented on a diff in the pull request:
https://github.com/apache/spark/pull/8984#discussion_r42263878
--- Diff: R/pkg/R/DataFrame.R ---
@@ -1880,4 +1880,46 @@ setMethod("as.data.frame",
stop(paste("Unused argument(s): ", paste(list(...),
collapse=", ")))
}
collect(x)
+ }
+)
+
+#' Returns the column types of a DataFrame.
+#'
+#' @name coltypes
+#' @title Get column types of a DataFrame
+#' @param x (DataFrame)
+#' @return value (character) A character vector with the column types of
the given DataFrame
+#' @rdname coltypes
+setMethod("coltypes",
+ signature(x = "DataFrame"),
+ function(x) {
+ # TODO: This may be moved as a global parameter
+ # These are the supported data types and how they map to
+ # R's data types
+ DATA_TYPES <- c("string"="character",
+ "long"="integer",
+ "tinyint"="integer",
+ "short"="integer",
+ "integer"="integer",
+ "byte"="integer",
+ "double"="numeric",
+ "float"="numeric",
+ "decimal"="numeric",
+ "boolean"="logical"
+ )
--- End diff --
The single character names are to reduce the amount of data serialized when
we transfer these data types to the JVM. Its not meant to be remembered by
anybody so I don't see it being a source of confusion. @sun-rui also added
tests which ensure these mappings don't break.
However I think having a list of primitive types, complex types and mapping
in a common file (types.R ?) sounds good to me.
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