paleolimbot commented on code in PR #13397:
URL: https://github.com/apache/arrow/pull/13397#discussion_r918309123
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r/R/compute.R:
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@@ -307,3 +307,157 @@ cast_options <- function(safe = TRUE, ...) {
)
modifyList(opts, list(...))
}
+
+#' Register user-defined functions
+#'
+#' These functions support calling R code from query engine execution
+#' (i.e., a [dplyr::mutate()] or [dplyr::filter()] on a [Table] or [Dataset]).
+#' Use [arrow_scalar_function()] to define an R function that accepts and
+#' returns R objects; use [arrow_advanced_scalar_function()] to define a
+#' lower-level function that operates directly on Arrow objects.
+#'
+#' @param name The function name to be used in the dplyr bindings
+#' @param scalar_function An object created with [arrow_scalar_function()]
+#' or [arrow_advanced_scalar_function()].
+#' @param in_type A [DataType] of the input type or a [schema()]
+#' for functions with more than one argument. This signature will be used
+#' to determine if this function is appropriate for a given set of arguments.
+#' If this function is appropriate for more than one signature, pass a
+#' `list()` of the above.
+#' @param out_type A [DataType] of the output type or a function accepting
+#' a single argument (`types`), which is a `list()` of [DataType]s. If a
+#' function it must return a [DataType].
+#' @param fun An R function or rlang-style lambda expression. This function
+#' will be called with R objects as arguments and must return an object
+#' that can be converted to an [Array] using [as_arrow_array()]. Function
+#' authors must take care to return an array castable to the output data
+#' type specified by `out_type`.
+#' @param advanced_fun An R function or rlang-style lambda expression. This
+#' function will be called with exactly two arguments: `kernel_context`,
+#' which is a `list()` of objects giving information about the
+#' execution context and `args`, which is a list of [Array] or [Scalar]
+#' objects corresponding to the input arguments.
Review Comment:
I added this to the documentation!
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