diff --git a/python/pyspark/rdd.py b/python/pyspark/rdd.py index 550c9dd80522fdf6ab5aa73f686ecb1da3a5c9dd..4f025b9f117076157c85130e51b9e2e2737e2ae9 100644 --- a/python/pyspark/rdd.py +++ b/python/pyspark/rdd.py @@ -316,9 +316,6 @@ class RDD(object): """ Return a sampled subset of this RDD (relies on numpy and falls back on default random generator if numpy is unavailable). - - >>> sc.parallelize(range(0, 100)).sample(False, 0.1, 2).collect() #doctest: +SKIP - [2, 3, 20, 21, 24, 41, 42, 66, 67, 89, 90, 98] """ assert fraction >= 0.0, "Negative fraction value: %s" % fraction return self.mapPartitionsWithIndex(RDDSampler(withReplacement, fraction, seed).func, True) diff --git a/python/pyspark/rddsampler.py b/python/pyspark/rddsampler.py index 528a181e8905a1dfef39e5f77023c6f59186e8c8..f5c3cfd259a5bf5ffb28360615debb44e692bf3b 100644 --- a/python/pyspark/rddsampler.py +++ b/python/pyspark/rddsampler.py @@ -40,14 +40,13 @@ class RDDSamplerBase(object): def initRandomGenerator(self, split): if self._use_numpy: import numpy - self._random = numpy.random.RandomState(self._seed) + self._random = numpy.random.RandomState(self._seed ^ split) else: - self._random = random.Random(self._seed) + self._random = random.Random(self._seed ^ split) - for _ in range(0, split): - # discard the next few values in the sequence to have a - # different seed for the different splits - self._random.randint(0, 2 ** 32 - 1) + # mixing because the initial seeds are close to each other + for _ in xrange(10): + self._random.randint(0, 1) self._split = split self._rand_initialized = True diff --git a/python/pyspark/tests.py b/python/pyspark/tests.py index 37a128907b3a73050fc112592c45f605f6448b9f..253a471849c3a4399ef7b23b3a58af48a366dca2 100644 --- a/python/pyspark/tests.py +++ b/python/pyspark/tests.py @@ -648,6 +648,21 @@ class RDDTests(ReusedPySparkTestCase): self.assertEquals(result.getNumPartitions(), 5) self.assertEquals(result.count(), 3) + def test_sample(self): + rdd = self.sc.parallelize(range(0, 100), 4) + wo = rdd.sample(False, 0.1, 2).collect() + wo_dup = rdd.sample(False, 0.1, 2).collect() + self.assertSetEqual(set(wo), set(wo_dup)) + wr = rdd.sample(True, 0.2, 5).collect() + wr_dup = rdd.sample(True, 0.2, 5).collect() + self.assertSetEqual(set(wr), set(wr_dup)) + wo_s10 = rdd.sample(False, 0.3, 10).collect() + wo_s20 = rdd.sample(False, 0.3, 20).collect() + self.assertNotEqual(set(wo_s10), set(wo_s20)) + wr_s11 = rdd.sample(True, 0.4, 11).collect() + wr_s21 = rdd.sample(True, 0.4, 21).collect() + self.assertNotEqual(set(wr_s11), set(wr_s21)) + class ProfilerTests(PySparkTestCase):