returning correct dtype from unitvec

matutils.unitvec currently returns a unitvector of a different dtype from the input vector if the input dtype isn't np.float.

we should make the return type consistent with the input type.

fixes piskvorky#1722

gensim/matutils.py

@@ -420,7 +420,7 @@ def unitvec(vec, norm='l2'):
             return vec
 
     if isinstance(vec, np.ndarray):
-        vec = np.asarray(vec, dtype=float)
+        vec = np.asarray(vec, dtype=vec.dtype)
         if norm == 'l1':
             veclen = np.sum(np.abs(vec))
         if norm == 'l2':

gensim/test/test_matutils.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Licensed under the GNU LGPL v2.1 - http://www.gnu.org/licenses/lgpl.html
+
+"""
+Automated tests for checking various matutils functions.
+"""
+
+import logging
+import unittest
+
+import numpy as np
+
+from gensim import matutils
+
+
+class TestMatutils(unittest.TestCase):
+    def test_unitvec(self):
+        input_vector = np.random.uniform(size=(100,)).astype(np.float32)
+        unit_vector = matutils.unitvec(input_vector)
+        self.assertEqual(input_vector.dtype, unit_vector.dtype)
+
+
+if __name__ == '__main__':
+    logging.root.setLevel(logging.WARNING)
+    unittest.main()