Christian Schwartze wrote:
> Following code could be one approach:
>
> os.system("cat %s | r.recode input=map_a output=map_recl" % path_to_rules)
>
> where path_to_rules is a previously created (temp) file containg the
> reclassifiying rules as for example:
os.system() shouldn't be used. E.g. the above will fail if
path_to_rules contains spaces (as is often the case on Windows).
The preferred approach for the above command is:
grass.run_command("r.recode", input="map_a",
output="map_recl", rules = path_to_rules)
If you have a command which requires input via stdin (rather from a
named file), use e.g.:
rules_f = open(path_to_rules, "r")
try:
grass.run_command("r.recode", input="map_a",
output="map_recl", stdin = rules_f)
finally:
rules_f.close()
Or, if you can rely upon Python 2.5 or later, use:
from __future__ import with_statement
with open(path_to_rules, "r") as rules_f:
grass.run_command("r.recode", input="map_a",
output="map_recl", stdin = rules_f)
Also, even in shell scripts "cat file | command" is suboptimal; use
"command < file" instead.
--
Glynn Clements
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