gdalwarp from within python script misbehaving

Question

I'm trying to run gdalwarp from within a python script

 start = "gdalwarp -overwrite -ts 22 20 -r average -srcnodata 99 "
 input_file = filename[12:]
 output_file = "temp1.tif"
 print start + input_file + ' ' +output_file
 subprocess.call([r'%s %s output.tif' % (start, input_file)], shell=True )

Where filename changes iteratively (i'm batch processing and this is the first step). However when i run the script i get for example:

ERROR 4: `200301.h11v09.tif' not recognised as a supported file format.

But when i run the code on 200301.h11v09.tif in terminal it works perfectly. I feel like it's something to do with python string substitution but don't know enough to figure out myself now.

Any ideas?

• ustroetz: Can you try it with a different filename. It might fail because of the two dots in your filename.
• James: Makes no difference unfortunately same error with 200301h11v09.tif :(

Answer 1

Drop the brackets around the first argument to subprocess.call. It's designed to take either a the command string as a single argument, or as a list of arguments that will be separated by a space. Here you are supplying the whole argument in one, so give it as a string, not a list.