Add single core mode to CoherenceModel. Fix #1683 (#1685)

* fix #1683 - no single core mode

* Update setup.py

gensim/models/coherencemodel.py

@@ -215,7 +215,7 @@ def __init__(self, model=None, topics=None, texts=None, corpus=None, dictionary=
         self._topics = None
         self.topics = topics
 
-        self.processes = processes if processes > 1 else max(1, mp.cpu_count() - 1)
+        self.processes = processes if processes >= 1 else max(1, mp.cpu_count() - 1)
 
     @classmethod
     def for_models(cls, models, dictionary, topn=20, **kwargs):

gensim/test/test_coherencemodel.py

@@ -13,6 +13,7 @@
 import tempfile
 import unittest
 from unittest import SkipTest
+import multiprocessing as mp
 
 import numpy as np
 from gensim.corpora.dictionary import Dictionary
@@ -213,6 +214,22 @@ def testErrors(self):
             coherence='u_mass'
         )
 
+    def testProcesses(self):
+        cpu = mp.cpu_count()
+        get_model = lambda p: CoherenceModel(
+            topics=self.topics1, corpus=self.corpus, dictionary=self.dictionary, coherence='u_mass', processes=p,
+        )
+
+        model = CoherenceModel(
+            topics=self.topics1, corpus=self.corpus, dictionary=self.dictionary, coherence='u_mass',
+        )
+        self.assertEqual(model.processes, cpu - 1)
+        for p in range(-2, 1):
+            self.assertEqual(get_model(p).processes, cpu - 1)
+
+        for p in range(1, 4):
+            self.assertEqual(get_model(p).processes, p)
+
     def testPersistence(self):
         fname = testfile()
         model = CoherenceModel(

setup.py

@@ -231,7 +231,7 @@ def finalize_options(self):
     'scikit-learn',
     'pyemd',
     'annoy',
-    'tensorflow >= 1.1.0',
+    'tensorflow <= 1.3.0',
     'keras >= 2.0.4',
 ]