Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/3264#discussion_r20373577
--- Diff: python/pyspark/context.py ---
@@ -289,12 +289,31 @@ def stop(self):
def parallelize(self, c, numSlices=None):
"""
- Distribute a local Python collection to form an RDD.
-
- >>> sc.parallelize(range(5), 5).glom().collect()
- [[0], [1], [2], [3], [4]]
- """
- numSlices = numSlices or self.defaultParallelism
+ Distribute a local Python collection to form an RDD. Use xrange if
+ the input represents a range for performance.
+
+ >>> sc.parallelize([0, 2, 3, 4, 6], 5).glom().collect()
+ [[0], [2], [3], [4], [6]]
+ >>> sc.parallelize(xrange(0, 6, 2), 5).glom().collect()
+ [[], [0], [], [2], [4]]
+ """
+ numSlices = int(numSlices) if numSlices is not None else
self.defaultParallelism
+ if isinstance(c, xrange):
+ size = len(c)
+ if size == 0:
+ return self.parallelize([], numSlices)
+ step = c[1] - c[0] if size > 1 else 1
+ c1 = xrange(c[0], c[0] + (size + 1) * step, step)
+
--- End diff --
Yes, this is better!
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