.TH r.out.mat 1grass "" "GRASS 8.3.2" "GRASS GIS User's Manual"
.SH NAME
\fI\fBr.out.mat\fR\fR  \- Exports a GRASS raster to a binary MAT\-File.
.SH KEYWORDS
raster, export, output
.SH SYNOPSIS
\fBr.out.mat\fR
.br
\fBr.out.mat \-\-help\fR
.br
\fBr.out.mat\fR \fBinput\fR=\fIname\fR \fBoutput\fR=\fIname\fR  [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBinput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input raster map
.IP "\fBoutput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name for output binary MAT file
.SH DESCRIPTION
\fIr.out.mat\fR will export a GRASS raster map to a MAT\-File which can
be loaded into Matlab or Octave for plotting or further analysis.
Attributes such as map title and bounds will also be exported into
additional array variables.
.br
.br
Specifically, the following array variables are created:
.br
.RS 4n
.IP \(bu 4n
\fB map_data\fR
.IP \(bu 4n
\fB map_name\fR
.IP \(bu 4n
\fB map_title\fR (if it exists)
.IP \(bu 4n
\fB map_northern_edge\fR
.IP \(bu 4n
\fB map_southern_edge\fR
.IP \(bu 4n
\fB map_eastern_edge\fR
.IP \(bu 4n
\fB map_western_edge\fR
.RE
.br
In addition, \fIr.out.mat\fR makes for a nice binary container format
for transferring georeferenced maps around, even if you don\(cqt use Matlab
or Octave.
.SH NOTES
\fIr.out.mat\fR exports a Version 4 MAT\-File. These files should
successfully load into more modern versions of Matlab and Octave
without any problems.
.br
.br
Everything should be Endian safe, so the resultant file can be simply
copied between different system architectures without binary translation.
.br
.br
As there is no IEEE value for NaN for integer maps, GRASS\(cqs null
value is used to represent it within these maps. You\(cqll have to do something
like this to clean them once the map is loaded into Matlab:
.br
.nf
\fC
    map_data(find(map_data < \-1e9)) = NaN;
\fR
.fi
Null values in maps containing either floating point or double\-precision
floating point data should translate into NaN values as expected.
.br
.br
\fIr.out.mat\fR must load the entire map into memory before writing,
therefore it might have problems with \fIhuge\fR maps.
(a 3000x4000 DCELL map uses about 100mb RAM)
.br
.br
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 the map\(cqs resolution information:
.br
.nf
\fC
    [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
\fR
.fi
.br
.SH EXAMPLE
In Matlab, plot with either:
.br
.nf
\fC
imagesc(map_data), axis equal, axis tight, colorbar
\fR
.fi
or
.br
.nf
\fC
contourf(map_data, 24), axis ij, axis equal, axis tight, colorbar
\fR
.fi
.br
.SH TODO
Add support for exporting map history, category information, color map, etc.
.br
Option to export as a version 5 MAT\-File, with map and support information
stored in a single structured array.
.SH SEE ALSO
\fI
r.in.mat
.br
r.out.ascii, r.out.bin
.br
r.null
.br
The Octave project
\fR
.SH AUTHOR
Hamish Bowman
.br
\fI
Department of Marine Science
.br
University of Otago
.br
New Zealand\fR
.br
.SH SOURCE CODE
.PP
Available at:
r.out.mat source code
(history)
.PP
Accessed: Friday Mar 08 07:34:34 2024
.PP
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.PP
© 2003\-2024
GRASS Development Team,
GRASS GIS 8.3.2 Reference Manual