Features/random seeds

lshash/lshash.py

@@ -42,10 +42,14 @@ class LSHash(object):
         stored if the file does not exist yet.
     :param overwrite:
         (optional) Whether to overwrite the matrices file if it already exist
+    :param seed
+        (optional) Seed for PRNG. To get consistant results over multiple
+        instantiation you must use the same seed.
     """
 
     def __init__(self, hash_size, input_dim, num_hashtables=1,
-                 storage_config=None, matrices_filename=None, overwrite=False):
+                 storage_config=None, matrices_filename=None,
+                 overwrite=False, seed=None):
 
         self.hash_size = hash_size
         self.input_dim = input_dim
@@ -60,6 +64,9 @@ def __init__(self, hash_size, input_dim, num_hashtables=1,
         self.matrices_filename = matrices_filename
         self.overwrite = overwrite
 
+        self.seed = seed
+        np.random.seed(self.seed)
+
         self._init_uniform_planes()
         self._init_hashtables()
 

tests/test_seed.py

@@ -0,0 +1,15 @@
+import lshash
+import numpy as np
+
+def test_fixed_seed():
+    """ fixed seeds should generate the same uniform_planes """
+    fixed_seed_lsh = [lshash.LSHash(10, 100, seed=20) for i in range(10)]
+    uniform_plane_sum = [np.sum(ls.uniform_planes) for ls in fixed_seed_lsh]
+    assert len(set(uniform_plane_sum)) == 1
+
+def test_nonfixed_seed():
+    """ when seed is not specified uniform planes should be different """
+    nonfixed_seed_lsh = [lshash.LSHash(10, 100) for i in range(10)]
+    uniform_plane_sum = [np.sum(ls.uniform_planes) for ls in nonfixed_seed_lsh]
+    assert len(set(uniform_plane_sum)) > 1
+