add check_random_state in utils

Author: rflamary

ot/utils.py

@@ -225,6 +225,26 @@ def check_params(**kwargs):
     return check
 
 
+def check_random_state(seed):
+    """Turn seed into a np.random.RandomState instance
+    Parameters
+    ----------
+    seed : None | int | instance of RandomState
+        If seed is None, return the RandomState singleton used by np.random.
+        If seed is an int, return a new RandomState instance seeded with seed.
+        If seed is already a RandomState instance, return it.
+        Otherwise raise ValueError.
+    """
+    if seed is None or seed is np.random:
+        return np.random.mtrand._rand
+    if isinstance(seed, (int, np.integer)):
+        return np.random.RandomState(seed)
+    if isinstance(seed, np.random.RandomState):
+        return seed
+    raise ValueError('{} cannot be used to seed a numpy.random.RandomState'
+                     ' instance'.format(seed))
+
+
 class deprecated(object):
 
     """Decorator to mark a function or class as deprecated.