Github user adrian555 commented on a diff in the pull request:
https://github.com/apache/spark/pull/9443#discussion_r43930565
--- Diff: R/pkg/R/DataFrame.R ---
@@ -2045,3 +2045,34 @@ setMethod("attach",
}
attach(newEnv, pos = pos, name = name, warn.conflicts =
warn.conflicts)
})
+
+#' Evaluate a R expression in an environment constructed from a DataFrame
+#' with() allows access to columns of a DataFrame by simply referring to
+#' their name. It appends every column of a DataFrame into a new
+#' environment. Then, the given expression is evaluated in this new
+#' environment.
+#'
+#' @rdname with
+#' @title Evaluate a R expression in an environment constructed from a
DataFrame
+#' @param data (DataFrame) DataFrame to use for constructing an
environment.
+#' @param expr (expression) Expression to evaluate.
+#' @param ... arguments to be passed to future methods.
+#' @examples
+#' \dontrun{
+#' with(irisDf, nrow(Sepal_Width))
+#' }
+#' @seealso \link{attach}
+setMethod("with",
+ signature(data = "DataFrame"),
+ function(data, expr, ...) {
+ stopifnot(!missing(data))
+ stopifnot(inherits(data, "DataFrame"))
+ cols <- columns(data)
+ stopifnot(length(cols) > 0)
+
+ newEnv <- new.env()
+ for (i in 1:length(cols)) {
+ assign(x = cols[i], value = data[, cols[i]], envir = newEnv)
+ }
--- End diff --
Certainly I can create an internal function for this. Any rule and
suggestion on where to put and what I should name the function? Thanks.
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