From 4caa27bb34bc754363282cd47eb2442dc571d031 Mon Sep 17 00:00:00 2001
From: Christoph Groth <christoph.groth@cea.fr>
Date: Mon, 5 Mar 2012 14:19:24 +0100
Subject: [PATCH] graph: use Cython's loop-over-sliced-complex-pointers feature
to make loops nicer
---
README.txt | 4 ++--
kwant/graph/core.pyx | 43 +++++++++++++++++++++----------------------
2 files changed, 23 insertions(+), 24 deletions(-)
diff --git a/README.txt b/README.txt
index 7550f09..6540d0f 100644
--- a/README.txt
+++ b/README.txt
@@ -105,8 +105,8 @@ Some conventions to keep in mind:
break existing tests.
Several modules are written in `Cython <http://cython.org/>`_ (.pyx file name
-extension). You will need Cython if you want to modify them. Turn on
-cythonization by passing the option ``--run-cython`` to setup.py.
+extension). You will need Cython (>= 0.15) if you want to modify them. Turn
+on cythonization by passing the option ``--run-cython`` to setup.py.
Tests
diff --git a/kwant/graph/core.pyx b/kwant/graph/core.pyx
index 8f0abd7..478a668 100644
--- a/kwant/graph/core.pyx
+++ b/kwant/graph/core.pyx
@@ -198,6 +198,7 @@ cdef class Graph:
cdef gint *tbuf = result.tails_idxs + 1, *tails = result.tails
cdef gint *edge_ids = result.edge_ids
cdef gint edge_id = 0, num_edges # = 0 is there to silence warning.
+ cdef Edge *edge
# `hbuf` is just `heads_idxs` shifted by one. We will use `hbuf` to
# build up `heads` and its end state will be such that `heads_idxs`
@@ -209,11 +210,11 @@ cdef class Graph:
memset(result.heads_idxs, 0, (self._num_nodes + 1) * sizeof(gint))
if twoway:
memset(result.tails_idxs, 0, (self._num_nodes + 1) * sizeof(gint))
- for edge_nr in range(self.size):
- if self.edges[edge_nr].tail >= 0:
- hbuf[self.edges[edge_nr].tail] += 1
- if twoway and self.edges[edge_nr].head >= 0:
- tbuf[self.edges[edge_nr].head] += 1
+ for edge in self.edges[:self.size]:
+ if edge.tail >= 0:
+ hbuf[edge.tail] += 1
+ if twoway and edge.head >= 0:
+ tbuf[edge.head] += 1
# Replace `hbuf` with its "antiderivative" and then subtract the
# original `hbuf` from it. This is done in one pass.
@@ -231,27 +232,26 @@ cdef class Graph:
# Iterate through all edges and build `heads` and `tails`.
next_np_edge_id = result.num_px_edges
- for edge_nr in range(self.size):
- edge = self.edges[edge_nr]
- head = edge.head
- tail = edge.tail
- if tail >= 0:
- edge_id = hbuf[tail]
- hbuf[tail] += 1
+ edge_nr = 0
+ for edge in self.edges[:self.size]:
+ if edge.tail >= 0:
+ edge_id = hbuf[edge.tail]
+ hbuf[edge.tail] += 1
elif twoway:
- assert head >= 0
+ assert edge.head >= 0
edge_id = next_np_edge_id
next_np_edge_id += 1
else:
edge_id = -1
if edge_id >= 0:
- heads[edge_id] = head
- if twoway and head >= 0:
- tails[tbuf[head]] = tail
- edge_ids[tbuf[head]] = edge_id
- tbuf[head] += 1
+ heads[edge_id] = edge.head
+ if twoway and edge.head >= 0:
+ tails[tbuf[edge.head]] = edge.tail
+ edge_ids[tbuf[edge.head]] = edge_id
+ tbuf[edge.head] += 1
if edge_nr_translation:
result.edge_ids_by_edge_nr[edge_nr] = edge_id
+ edge_nr += 1
assert result.num_edges == next_np_edge_id
return result
@@ -262,11 +262,10 @@ cdef class Graph:
That resulting file can be visualized with dot(1) or neato(1) form the
graphviz package.
"""
- cdef gint edge_nr
+ cdef Edge *edge
file.write("digraph g {\n")
- for edge_nr in range(self.size):
- file.write(" %d -> %d;\n" %
- (self.edges[edge_nr].tail, self.edges[edge_nr].head))
+ for edge in self.edges[:self.size]:
+ file.write(" %d -> %d;\n" % (edge.tail, edge.head))
file.write("}\n")
--
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