Merge pull request #450 from arcondello/fix/sampleset.samples-iterator

Make SampleSet.samples an iterator

dimod/views/samples.py

@@ -69,8 +69,10 @@ def __iter__(self):
         return iter(self._mapping._data.flat)
 
 
-class SamplesArray(abc.Sequence):
-    __slots__ = ('_samples', '_variables')
+# developer note: Iterator functionality is deprecated
+class SamplesArray(abc.Sequence, abc.Iterator):
+    __slots__ = ('_samples', '_variables',
+                 '_itercount')  # used for deprecated iteration feature
 
     def __init__(self, samples, variables):
         self._samples = samples
@@ -136,5 +138,20 @@ def __iter__(self):
         for row in self._samples:
             yield SampleView(row, variables)
 
+    def __next__(self):
+        import warnings
+        msg = ("SampleSet.samples() will return an iterable not an iterator in "
+               "the future")
+        warnings.warn(msg, DeprecationWarning)
+
+        itercount = getattr(self, '_itercount', 0)
+        if itercount < len(self):
+            self._itercount = itercount + 1
+            return self[itercount]
+        raise StopIteration
+
+    next = __next__  # for python2
+
+
     def __len__(self):
         return self._samples.shape[0]

tests/test_sampleset.py

@@ -16,6 +16,11 @@
 import unittest
 import json
 
+try:
+    import collections.abc as abc
+except ImportError:
+    import collections as abc
+
 from collections import OrderedDict
 
 import numpy as np
@@ -354,6 +359,15 @@ def test_data_reverse(self):
         reversed_samples = list(sampleset.data(reverse=True))
         self.assertEqual(samples, list(reversed(reversed_samples)))
 
+    def test_iterator(self):
+        # deprecated feature
+        bqm = dimod.BinaryQuadraticModel.from_ising({}, {'ab': -1})
+        sampleset = dimod.SampleSet.from_samples_bqm([{'a': -1, 'b': 1}, {'a': 1, 'b': 1}], bqm)
+        self.assertIsInstance(sampleset.samples(), abc.Iterator)
+        self.assertIsInstance(sampleset.samples(n=2), abc.Iterator)
+        spl = next(sampleset.samples())
+        self.assertEqual(spl, {'a': 1, 'b': 1})
+
 
 class TestSerialization(unittest.TestCase):
     def test_empty_with_bytes(self):