[Yt-svn] yt: Cache particle indices, which speeds things up a surprising ...

[hg at spacepope.org]

hg Repository: yt
details:   yt/rev/d9bdb37f8046
changeset: 3369:d9bdb37f8046
user:      Matthew Turk <matthewturk at gmail.com>
date:
Thu Sep 02 00:07:45 2010 -0700
description:
Cache particle indices, which speeds things up a surprising amount...

diffstat:

 yt/frontends/flash/data_structures.py |  2 ++
 yt/frontends/flash/io.py              |  4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diffs (26 lines):

diff -r e2b55f386569 -r d9bdb37f8046 yt/frontends/flash/data_structures.py
--- a/yt/frontends/flash/data_structures.py	Wed Sep 01 23:34:38 2010 -0700
+++ b/yt/frontends/flash/data_structures.py	Thu Sep 02 00:07:45 2010 -0700
@@ -115,6 +115,8 @@
                               for ax in 'xyz']
         self.grid_dimensions[:] *= (nxb, nyb, nzb)
         self.grid_particle_count[:] = f["/localnp"][:][:,None]
+        self._particle_indices = na.zeros(self.num_grids + 1, dtype='int64')
+        na.add.accumulate(self.grid_particle_count, out=self._particle_indices[1:])
         # This will become redundant, as _prepare_grid will reset it to its
         # current value.  Note that FLASH uses 1-based indexing for refinement
         # levels, but we do not, so we reduce the level by 1.
diff -r e2b55f386569 -r d9bdb37f8046 yt/frontends/flash/io.py
--- a/yt/frontends/flash/io.py	Wed Sep 01 23:34:38 2010 -0700
+++ b/yt/frontends/flash/io.py	Thu Sep 02 00:07:45 2010 -0700
@@ -69,8 +69,8 @@
         f = self._handle
         if field in self._particle_fields:
             if grid.NumberOfParticles == 0: return na.array([], dtype='float64')
-            start = na.sum(self.pf.h.grid_particle_count[:grid.id-grid._id_offset])
-            end = start + grid.NumberOfParticles
+            start = self.pf.h._particle_indices[grid.id - grid._id_offset]
+            end = self.pf.h._particle_indices[grid.id - grid._id_offset + 1]
             fi = self._particle_fields[field]
             tr = f["/tracer particles"][start:end, fi]
         else: