Github user olarayej commented on a diff in the pull request:
https://github.com/apache/spark/pull/11569#discussion_r57342255
--- Diff: R/pkg/R/functions.R ---
@@ -2638,3 +2638,81 @@ setMethod("sort_array",
jc <- callJStatic("org.apache.spark.sql.functions",
"sort_array", x@jc, asc)
column(jc)
})
+
+#' This function computes a histogram for a given SparkR Column.
+#'
+#' @name histogram
+#' @title Histogram
+#' @param nbins the number of bins (optional). The default is 10.
+#' @param df the DataFrame containing the Column to build the histogram
from.
+#' @param colname the name of the column to build the histogram from.
+#' @return a data.frame with the histogram statistics, i.e., counts and
centroids.
+#' @examples \dontrun{
+#'
+#' # Create a DataFrame from the Iris dataset
+#' irisDF <- createDataFrame(sqlContext, iris)
+#'
+#' # Compute histogram statistics
+#' histData <- histogram(df, "colname"Sepal_Length", nbins = 12)
+#'
+#' # Once SparkR has computed the histogram statistics, it would be very
easy to
+#' # render the histogram using R's visualization packages such as ggplot2.
+#'
+#' }
+setMethod("histogram",
+ signature(df = "DataFrame"),
+ function(df, colname, nbins = 10) {
+ # Validate nbins
+ if (nbins < 2) {
+ stop("The number of bins must be a positive integer number
greater than 1.")
--- End diff --
R doesn't (see below). Let me change my code so it rounds nbins to the
lowest integer.
> str(hist(iris$Sepal.Length, breaks=10.5))
List of 6
$ breaks : num [1:9] 4 4.5 5 5.5 6 6.5 7 7.5 8
$ counts : int [1:8] 5 27 27 30 31 18 6 6
$ density : num [1:8] 0.0667 0.36 0.36 0.4 0.4133 ...
$ mids : num [1:8] 4.25 4.75 5.25 5.75 6.25 6.75 7.25 7.75
$ xname : chr "iris$Sepal.Length"
$ equidist: logi TRUE
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