[GRASS-SVN] r55789 - grass/branches/releasebranch_6_4/lib/python

[svn_grass at osgeo.org]

Author: hamish
Date: 2013-04-14 03:04:08 -0700 (Sun, 14 Apr 2013)
New Revision: 55789

Modified:
   grass/branches/releasebranch_6_4/lib/python/raster.py
Log:
backport raster.mapcalc_start() from devbr6, allows parallelizing mapcalc calls.

Modified: grass/branches/releasebranch_6_4/lib/python/raster.py
===================================================================
--- grass/branches/releasebranch_6_4/lib/python/raster.py	2013-04-14 09:48:27 UTC (rev 55788)
+++ grass/branches/releasebranch_6_4/lib/python/raster.py	2013-04-14 10:04:08 UTC (rev 55789)
@@ -108,3 +108,42 @@
 
     if write_command('r.mapcalc', stdin = e, env = env) != 0:
 	fatal(_("An error occurred while running r.mapcalc"))
+
+
+def mapcalc_start(exp, quiet = False, verbose = False, overwrite = False, **kwargs):
+    """!Interface to r.mapcalc, doesn't wait for it to finish, returns Popen object.
+
+    \code
+    >>> expr1 = '"%s" = "%s" * 10' % (output, input)
+    >>> expr2 = '...'   # etc.
+    >>> # launch the jobs:
+    >>> p1 = grass.mapcalc_start(expr1)
+    >>> p2 = grass.mapcalc_start(expr2)   # etc.
+    ...
+    >>> # wait for them to finish:
+    >>> p1.wait()
+    >>> p2.wait()   # etc.
+    \endcode
+
+    @param exp expression
+    @param kwargs
+    
+    @return Popen object
+    """
+    t = string.Template(exp)
+    e = t.substitute(**kwargs)
+
+    env = os.environ.copy()
+    if quiet:
+        env['GRASS_VERBOSE'] = '0'
+    if verbose:
+        env['GRASS_VERBOSE'] = '3'
+    if overwrite:
+        env['GRASS_OVERWRITE'] = '1'
+
+    stdin = e
+    p = feed_command('r.mapcalc', env = env, **kwargs)
+    p.stdin.write(stdin)
+    p.stdin.close()
+
+    return p