Hi All,
I've attached a patch which optimizes a particular case of the
RegularPolyCollection.get_transformed_patches method. This is
particularly useful when using a picker on a scatter plot with ~40,000
points (as I happen to be doing) and cuts the time spent in this
function from ~4s to ~1s, which accounts for about 50% of the lag in
my particular use case.
Similar improvements might be possible in the N > 1 case, but I don't
have a) a data set or b) the time to work them out with, so hopefully
someone is happy to check in this patch as it stands, as I think the
N==1 is probably the common case.
If there are any problems with the patch let me know and I'll try to
fix it up. It's against latest svn (3262)
Cheers,
Tim
Index: lib/matplotlib/collections.py
===================================================================
--- lib/matplotlib/collections.py (revision 3262)
+++ lib/matplotlib/collections.py (working copy)
@@ -153,7 +153,7 @@
if not self.pickable(): return
ind = []
x, y = mouseevent.x, mouseevent.y
- for i, thispoly in enumerate(self.get_transformed_patches()):
+ for i, thispoly in enumerate(self.get_transformed_patches()):
inside = nxutils.pnpoly(x, y, thispoly)
if inside: ind.append(i)
if len(ind):
@@ -167,7 +167,6 @@
The ith element in the returned sequence is a list of x,y
vertices defining the ith polygon
"""
-
verts = self._verts
offsets = self._offsets
usingOffsets = offsets is not None
@@ -451,13 +450,19 @@
__init__.__doc__ = dedent(__init__.__doc__) % kwdocd
def get_transformed_patches(self):
-
+
xverts, yverts = zip(*self._verts)
xverts = asarray(xverts)
yverts = asarray(yverts)
sizes = sqrt(asarray(self._sizes)*self._dpi.get()/72.0)
Nsizes = len(sizes)
transOffset = self.get_transoffset()
+
+ # optimize this case for an approx 4x speedup
+ if Nsizes == 1:
+ xy = asarray([xverts, yverts]).T * sizes[0]
+ polys = [xy + offset for offset in transOffset.seq_xy_tups(self._offsets)]
+
polys = []
for i, loc in enumerate(self._offsets):
xo,yo = transOffset.xy_tup(loc)
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