Merge pull request #1561 from markotoplak/domainhash

Avoid frequent recomputation of domain hashes.
biolab · Sep 16, 2016 · 6d039f1 · 6d039f1
2 parents 79881fa + e2df3f7
commit 6d039f1
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/Orange/data/domain.py b/Orange/data/domain.py
@@ -131,6 +131,9 @@ def __init__(self, attributes, class_vars=None, metas=None, source=None):
         self._known_domains = weakref.WeakKeyDictionary()
         self._last_conversion = None
 
+        # Precompute hash, which is frequently used in domain conversions.
+        self._hash = hash(self.attributes) ^ hash(self.class_vars) ^ hash(self.metas)
+
     # noinspection PyPep8Naming
     @classmethod
     def from_numpy(cls, X, Y=None, metas=None):
@@ -422,4 +425,4 @@ def __eq__(self, other):
                 self.metas == other.metas)
 
     def __hash__(self):
-        return hash(self.attributes) ^ hash(self.class_vars) ^ hash(self.metas)
+        return self._hash