Github user CodingCat commented on a diff in the pull request:
https://github.com/apache/spark/pull/135#discussion_r10580163
--- Diff: core/src/main/scala/org/apache/spark/rdd/RDD.scala ---
@@ -310,6 +310,9 @@ abstract class RDD[T: ClassTag](
* Return a sampled subset of this RDD.
*/
def sample(withReplacement: Boolean, fraction: Double, seed: Int):
RDD[T] = {
+ if (fraction < Double.MinValue || fraction > Double.MaxValue) {
--- End diff --
Hi, @rxin , I'm also a bit confused here, I think the name of the argument
is a bit confusing
https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/rdd/RDD.scala#L357
The above line contains a multiplier to ensure that the sampling can return
enough sample points in most of cases..(I think so), so the fraction value can
actually be larger than 1
also, this value actually determines the mean value of Poisson/Bernoulli
distribution
https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/rdd/RDD.scala#L314
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