From 44751af9f8ec6a2b6ca49e5aee3e924c61afd3f7 Mon Sep 17 00:00:00 2001 From: Xiangrui Meng Date: Wed, 5 Nov 2014 10:30:10 -0800 Subject: [branch-1.1][SPARK-4148][PySpark] fix seed distribution and add some tests for rdd.sample Port #3010 to branch-1.1. Author: Xiangrui Meng Closes #3104 from mengxr/SPARK-4148-1.1 and squashes the following commits: 684c002 [Xiangrui Meng] apply SPARK-4148 to branch-1.1 --- python/pyspark/rdd.py | 3 --- python/pyspark/rddsampler.py | 11 +++++------ python/pyspark/tests.py | 15 +++++++++++++++ 3 files changed, 20 insertions(+), 9 deletions(-) (limited to 'python') diff --git a/python/pyspark/rdd.py b/python/pyspark/rdd.py index 2b47b6c18e..3f81550bbb 100644 --- a/python/pyspark/rdd.py +++ b/python/pyspark/rdd.py @@ -417,9 +417,6 @@ 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 55e247da0e..a6e81067cf 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, sys.maxint) + # 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 8f0a351b6b..5cea1b03ea 100644 --- a/python/pyspark/tests.py +++ b/python/pyspark/tests.py @@ -470,6 +470,21 @@ class TestRDDFunctions(PySparkTestCase): self.assertEquals(([1, "b"], [5]), rdd.histogram(1)) self.assertRaises(TypeError, lambda: rdd.histogram(2)) + 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 TestSQL(PySparkTestCase): -- cgit v1.2.3