Merge pull request #114 from fjosw/feat/obs_hash

hash method for Obs objects

pyerrors/obs.py

@@ -1,4 +1,5 @@
 import warnings
+import hashlib
 import pickle
 from math import gcd
 from functools import reduce
@@ -684,6 +685,15 @@ class Obs:
         else:
             return '{:.0f}({:2.0f})'.format(self.value, self._dvalue)
 
+    def __hash__(self):
+        hash_tuple = (np.array([self.value]).astype(np.float32).data.tobytes(),)
+        hash_tuple += tuple([o.astype(np.float32).data.tobytes() for o in self.deltas.values()])
+        hash_tuple += tuple([np.array([o.errsq()]).astype(np.float32).data.tobytes() for o in self.covobs.values()])
+        hash_tuple += tuple([o.encode() for o in self.names])
+        m = hashlib.md5()
+        [m.update(o) for o in hash_tuple]
+        return int(m.hexdigest(), 16) & 0xFFFFFFFF
+
     # Overload comparisons
     def __lt__(self, other):
         return self.value < other

tests/obs_test.py

@@ -950,3 +950,16 @@ def test_cobs_array():
     cobs * np.identity(4)
     np.identity(4) / cobs
     cobs / np.ones((4, 4))
+
+
+def test_hash():
+    obs = pe.pseudo_Obs(0.3, 0.1, "test") + pe.Obs([np.random.normal(2.3, 0.2, 200)], ["test2"], [range(1, 400, 2)])
+    o1 = obs + pe.cov_Obs(0.0, 0.1, "co") + pe.cov_Obs(0.0, 0.8, "co2")
+    o2 = obs + pe.cov_Obs(0.0, 0.2, "co") + pe.cov_Obs(0.0, 0.8, "co2")
+
+    for i_obs in [obs, o1, o2]:
+        assert hash(i_obs) == hash(i_obs ** 2 / i_obs) == hash(1 * i_obs)
+        assert hash(i_obs) == hash((1 + 1e-16) * i_obs)
+        assert hash(i_obs) != hash((1 + 1e-7) * i_obs)
+    assert hash(obs) != hash(o1)
+    assert hash(o1) != hash(o2)