cone/permutation_invariant.py: use generator expressions where applicable.

diff --git a/mjo/cone/permutation_invariant.py b/mjo/cone/permutation_invariant.py
index 7aad31e9e709114524bedd3f1354219867a99c57..d87ace2be9a034264b497586130bc6a3492e9be2 100644 (file)
--- a/mjo/cone/permutation_invariant.py
+++ b/mjo/cone/permutation_invariant.py
@@ -33,17 +33,12 @@ def random_permutation_invariant_cone(lattice=None,
     V = K.lattice().vector_space()
 
     # The set of all permutatin matrices on ``V``.
-    Sn = [ p.matrix() for p in SymmetricGroup(V.dimension()) ]
+    Sn = ( p.matrix() for p in SymmetricGroup(V.dimension()) )
 
     # Set of permuted generators
-    pgens = []
+    pgens = ( permutation*V(g) for permutation in Sn for g in K )
 
-    for g in K.rays():
-        for permutation in Sn:
-            pgens.append(permutation * V(g))
-
-    L = ToricLattice(V.dimension())
-    return Cone(pgens, lattice=L)
+    return Cone(pgens, K.lattice())
 
 
 def is_permutation_invariant(K):
@@ -60,9 +55,9 @@ def is_permutation_invariant(K):
 
     EXAMPLES::
 
-        sage: all([ is_permutation_invariant(rearrangement_cone(p,n))
+        sage: all( is_permutation_invariant(rearrangement_cone(p,n))
         ....:               for n in range(3, 6)
-        ....:               for p in range(1, n) ])
+        ....:               for p in range(1, n) )
         True
 
     """
@@ -71,13 +66,8 @@ def is_permutation_invariant(K):
     V = K.lattice().vector_space()
 
     # The set of all permutation matrices on ``V``.
-    Sn = [ p.matrix() for p in SymmetricGroup(V.dimension()) ]
-
-    for permutation in Sn:
-        L = ToricLattice(V.dimension())
-        permuted_gens = [ permutation * V(g) for g in K.rays() ]
-        for g in permuted_gens:
-            if not K.contains(g):
-                return False
+    Sn = ( p.matrix() for p in SymmetricGroup(V.dimension()) )
 
-    return True
+    return all(K.contains(permutation*V(g))
+                   for g in K
+                   for permutation in Sn)