r.in.mat(1grass) GRASS GIS User's Manual r.in.mat(1grass)
NAME
r.in.mat - Imports a binary MAT-File(v4) to a GRASS raster.
KEYWORDS
raster, import
SYNOPSIS
r.in.mat
r.in.mat --help
r.in.mat input=name [output=name] [--overwrite] [--help] [--ver-
bose] [--quiet] [--ui]
Flags:
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
input=name [required]
Name of input MAT-File(v4)
output=name
Name for output raster map (override)
DESCRIPTION
r.in.mat will import a GRASS raster map from a Version 4 MAT-File which
was created with Matlab or Octave. Attributes such as map title and
bounds will also be imported if they exist.
Specifically, the following array variables will be read:
•
map_data
•
map_name
•
map_title
•
map_northern_edge
•
map_southern_edge
•
map_eastern_edge
•
map_western_edge
Any other variables in the MAT-file will be simply skipped over.
The ’map_name’ variable is optional, if it exists, and is valid, the
new map will be thus named. If it doesn’t exist or a name is specified
with the output= option, the raster map’s name will be set to "MatFile"
or the name specified respectively. (maximum 64 characters; normal
GRASS naming rules apply)
The ’map_title’ variable is optional, the map’s title is set if it ex-
ists.
The ’map_northern_edge’ and like variables are mandatory unless the
user is importing to a "XY" non-georeferenced location (e.g. imagery
data). Latitude and longitude values should be in decimal form.
NOTES
r.in.mat imports a Version 4 MAT-File. These files can be successfully
created with more modern versions of Matlab and Octave (see "EXAMPLES"
below).
Everything should be Endian safe, so the file to be imported can be
simply copied between different system architectures without binary
translation (caveat: see "TODO" below).
As there is no IEEE value for NaN in integer arrays, GRASS’s null value
may be used to represent it within these maps. Usually Matlab will save
any integer based matrix with NaN values as a double-precision floating
point array, so this usually isn’t an issue. To save space, once the
map is loaded into GRASS you can convert it back to an integer map with
the following command:
r.mapcalc "int_map = int(MATFile_map)"
NaN values in either floating point or double-precision floating point
matrices should translate into null values as expected.
r.in.mat must load the entire map array into memory before writing,
therefore it might have problems with huge arrays. (a 3000x4000 DCELL
map uses about 100mb RAM)
GRASS defines its map bounds at the outer-edge of the bounding cells,
not at the coordinates of their centroids. Thus, the following Matlab
commands may be used to determine and check the map’s resolution infor-
mation will be correct:
[rows cols] = size(map_data)
x_range = map_eastern_edge - map_western_edge
y_range = map_northern_edge - map_southern_edge
ns_res = y_range/rows
ew_res = x_range/cols
Remember Matlab arrays are referenced as (row,column), i.e. (y,x).
In addition, r.in.mat and r.out.mat make for a nice binary container
format for transferring georeferenced maps around, even if you don’t
use Matlab or Octave.
EXAMPLES
In Matlab, save with:
save filename.mat map_* -v4
In Octave, save with:
save -mat4-binary filename.mat map_*
TODO
Robust support for mixed-Endian importation. (This is a work in
progress, please help by reporting any failures to the GRASS bug track-
ing system;
Add support for importing map history, category information, color map,
etc. if they exist.
Option to import a version 5 MAT-File, with map and support information
stored in a single structured array.
KNOWN ISSUES
If you encounter any problems, please contact the GRASS Development
Team.
SEE ALSO
r.out.mat, r.in.ascii, r.in.bin, r.mapcalc, r.null.
The Octave project
AUTHOR
Hamish Bowman
Department of Marine Science
University of Otago
New Zealand
SOURCE CODE
Available at: r.in.mat source code (history)
Accessed: unknown
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