diff --git a/kwant/builder.py b/kwant/builder.py
index 2af9f2753ba7986b979dca966c5846c1c541c714..24428ae7b216873d8af7d88b1cd38057339c435c 100644
--- a/kwant/builder.py
+++ b/kwant/builder.py
@@ -333,22 +333,16 @@ class Symmetry(metaclass=abc.ABCMeta):
pass
@abc.abstractmethod
- def isstrictsupergroup(self, other):
- """Test whether `self` is a strict supergroup of `other`...
+ def has_subgroup(self, other):
+ """Test whether `self` has the subgroup `other`...
or, in other words, whether `other` is a subgroup of `self`. The
- reason why this is the abstract method (and not `issubgroup`) is that
+ reason why this is the abstract method (and not `is_subgroup`) is that
in general it's not possible for a subgroup to know its supergroups.
"""
pass
- def issubgroup(self, other):
- """Test whether `self` is a subgroup of `other`."""
- return other.isstrictsupergroup(self)
-
- __le__ = issubgroup
-
class NoSymmetry(Symmetry):
"""A symmetry with a trivial symmetry group."""
@@ -389,8 +383,8 @@ class NoSymmetry(Symmetry):
raise ValueError('Generators must be empty for NoSymmetry.')
return NoSymmetry(generators)
- def isstrictsupergroup(self, other):
- return False
+ def has_subgroup(self, other):
+ return isinstance(other, NoSymmetry)
@@ -1303,7 +1297,7 @@ class Builder:
templ_sym = template.symmetry
# Check that symmetries are commensurate.
- if not self.symmetry <= templ_sym:
+ if not templ_sym.has_subgroup(self.symmetry):
raise ValueError("Builder symmetry is not a subgroup of the "
"template symmetry")
diff --git a/kwant/lattice.py b/kwant/lattice.py
index e57a6e27a06830e4face8d5ef48c79dd827abe45..8cf0d6a20065339ee389de2eb7cc2cc23cad074e 100644
--- a/kwant/lattice.py
+++ b/kwant/lattice.py
@@ -555,7 +555,7 @@ class TranslationalSymmetry(builder.Symmetry):
raise ValueError('Generators must be sequences of integers.')
return TranslationalSymmetry(*ta.dot(generators, self.periods))
- def isstrictsupergroup(self, other):
+ def has_subgroup(self, other):
if isinstance(other, builder.NoSymmetry):
return True
elif not isinstance(other, TranslationalSymmetry):
diff --git a/kwant/tests/test_builder.py b/kwant/tests/test_builder.py
index 9f6dc7442b94856c5ba8702ceaeb79ba1fe7ad9d..b1e5c6792c833e4316e51a29112c31acf49677b3 100644
--- a/kwant/tests/test_builder.py
+++ b/kwant/tests/test_builder.py
@@ -129,7 +129,7 @@ class VerySimpleSymmetry(builder.Symmetry):
def num_directions(self):
return 1
- def isstrictsupergroup(self, other):
+ def has_subgroup(self, other):
if isinstance(other, builder.NoSymmetry):
return True
elif isinstance(other, VerySimpleSymmetry):
@@ -652,32 +652,36 @@ def test_fill():
return -100 <= site.pos[0] < 100
## Test that copying a builder by "fill" preserves everything.
- cubic = kwant.lattice.general(ta.identity(3))
- sym = kwant.TranslationalSymmetry((3, 0, 0), (0, 4, 0), (0, 0, 5))
-
- # Make a weird system.
- orig = kwant.Builder(sym)
- sites = cubic.shape(lambda pos: True, (0, 0, 0))
- for i, site in enumerate(orig.expand(sites)):
- if i % 7 == 0:
- continue
- orig[site] = i
- for i, hopp in enumerate(orig.expand(cubic.neighbors(1))):
- if i % 11 == 0:
- continue
- orig[hopp] = i * 1.2345
- for i, hopp in enumerate(orig.expand(cubic.neighbors(2))):
- if i % 13 == 0:
- continue
- orig[hopp] = i * 1j
-
- # Clone the original using fill.
- clone = kwant.Builder(sym)
- clone.fill(orig, lambda s: True, (0, 0, 0))
-
- # Verify that both are identical.
- assert set(clone.site_value_pairs()) == set(orig.site_value_pairs())
- assert set(clone.hopping_value_pairs()) == set(orig.hopping_value_pairs())
+ for sym, func in [(kwant.TranslationalSymmetry(*np.diag([3, 4, 5])),
+ lambda pos: True),
+ (builder.NoSymmetry(),
+ lambda pos: ta.dot(pos, pos) < 17)]:
+ cubic = kwant.lattice.general(ta.identity(3))
+
+ # Make a weird system.
+ orig = kwant.Builder(sym)
+ sites = cubic.shape(func, (0, 0, 0))
+ for i, site in enumerate(orig.expand(sites)):
+ if i % 7 == 0:
+ continue
+ orig[site] = i
+ for i, hopp in enumerate(orig.expand(cubic.neighbors(1))):
+ if i % 11 == 0:
+ continue
+ orig[hopp] = i * 1.2345
+ for i, hopp in enumerate(orig.expand(cubic.neighbors(2))):
+ if i % 13 == 0:
+ continue
+ orig[hopp] = i * 1j
+
+ # Clone the original using fill.
+ clone = kwant.Builder(sym)
+ clone.fill(orig, lambda s: True, (0, 0, 0))
+
+ # Verify that both are identical.
+ assert set(clone.site_value_pairs()) == set(orig.site_value_pairs())
+ assert (set(clone.hopping_value_pairs())
+ == set(orig.hopping_value_pairs()))
## Test for warning when "start" is out.
target = builder.Builder()
diff --git a/kwant/tests/test_lattice.py b/kwant/tests/test_lattice.py
index c3ea78e7b17162d25a1b5314de5a51f1c507aa85..ab4cea6096c5b96235dd28619aeceab9e2dea5d6 100644
--- a/kwant/tests/test_lattice.py
+++ b/kwant/tests/test_lattice.py
@@ -251,21 +251,23 @@ def test_symmetry_act():
sym.act(ta.array(el), site)
-def test_symmetry_subgroup():
+def test_symmetry_has_subgroup():
rng = np.random.RandomState(0)
## test whether actual subgroups are detected as such
vecs = rng.randn(3, 3)
sym1 = lattice.TranslationalSymmetry(*vecs)
- assert sym1 >= sym1
- assert sym1 >= builder.NoSymmetry()
- assert sym1 >= lattice.TranslationalSymmetry(2 * vecs[0],
- 3 * vecs[1] + 4 * vecs[2])
- assert not sym1 <= lattice.TranslationalSymmetry(*(0.8 * vecs))
+ ns = builder.NoSymmetry()
+ assert ns.has_subgroup(ns)
+ assert sym1.has_subgroup(sym1)
+ assert sym1.has_subgroup(ns)
+ assert sym1.has_subgroup(lattice.TranslationalSymmetry(
+ 2 * vecs[0], 3 * vecs[1] + 4 * vecs[2]))
+ assert not lattice.TranslationalSymmetry(*(0.8 * vecs)).has_subgroup(sym1)
## test subgroup creation
for dim in range(1, 4):
generators = rng.randint(10, size=(dim, 3))
- assert sym1.subgroup(*generators) <= sym1
+ assert sym1.has_subgroup(sym1.subgroup(*generators))
# generators are not linearly independent
with raises(ValueError):