[GRASS-dev] question about the concept 'window'

Hamish hamish_b at yahoo.com
Tue Jul 20 01:24:04 EDT 2010


Peng Du wrote:
> Another question: is there any function similar to
> get_map_row(…) but gets a column of data from raster image
> rather than a row?

no. you'd have to load the whole map into memory for that, which
is no good for very large maps.

if you do have to do a lot of operations with full rows, and
your maps are very big, you might consider to rotate the map by
90 degrees (AFAIR there's a contrib/ module in GRASS 4 or 5 to
do that) or use r.out.mat to load the data into Matlab/Octave
whos native array layout is by rows not columns (Fortran style).
(but again they probably want to hold the whole array in memory)

Hamish


      


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