Changeset 7615:a1d368a08149

Timestamp:

12/12/07 07:50:58 (5 years ago)

Author:

William Stein <wstein@…>

Branch:

default

Message:

permutation conversion to tuples and hashing

Location:

sage/groups/perm_gps

Files:

• permgroup_element.pxd (modified) (1 diff)
• permgroup_element.pyx (modified) (1 diff)

sage/groups/perm_gps/permgroup_element.pxd

@@ -7 +7 @@
     cdef __gap
     cdef Element _gap_element
+    cdef __tuple
     cdef PermutationGroupElement _new_c(self)
     cpdef list(self)

sage/groups/perm_gps/permgroup_element.pyx

@@ -498 +498 @@
         return [self.perm[i]+1 for i from 0 <= i < self.n]
 
+    def __hash__(self):
+        """
+        Return hash of this permutation.
+
+        EXAMPLES:
+            sage: G = SymmetricGroup(5)
+            sage: s = G([2,1,5,3,4])
+            sage: s.tuple()
+            (2, 1, 5, 3, 4)
+            sage: hash(s)
+            1592966088
+            sage: hash(s.tuple())
+            1592966088
+        """
+        return hash(self.tuple())
+
+    def tuple(self):
+        """
+        Return tuple of images of integers under self.
+
+        EXAMPLES:
+            sage: G = SymmetricGroup(5)
+            sage: s = G([2,1,5,3,4])
+            sage: s.tuple()
+            (2, 1, 5, 3, 4)
+        """
+        if self.__tuple is None:
+            self.__tuple = tuple(self.list())
+        return self.__tuple
+
     def dict(self):
         """