r.out.mat(1)

1r.out.mat(1)                  Grass User's Manual                 r.out.mat(1)
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NAME

6       r.out.mat  - Exports a GRASS raster to a binary MAT-File.
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KEYWORDS

9       raster, export
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SYNOPSIS

12       r.out.mat
13       r.out.mat help
14       r.out.mat [-v] input=name output=string  [--verbose]  [--quiet]
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16   Flags:
17       -v
18           Verbose mode
19
20       --verbose
21           Verbose module output
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23       --quiet
24           Quiet module output
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26   Parameters:
27       input=name
28           Name of input raster map
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30       output=string
31           Name for the output binary MAT-File
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DESCRIPTION

34       r.out.mat  will  export  a  GRASS raster map to a MAT-File which can be
35       loaded  into  Matlab  or  Octave  for  plotting  or  further  analysis.
36       Attributes  such  as  map  title  and bounds will also be exported into
37       additional array variables.
38       Specifically, the following array variables are created:
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40                      map_data
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42                      map_name
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44                      map_title (if it exists)
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46                      map_northern_edge
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48                      map_southern_edge
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50                      map_eastern_edge
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52                      map_western_edge
53       In addition, r.out.mat makes for a nice  binary  container  format  for
54       transferring georeferenced maps around, even if you don't use Matlab or
55       Octave.
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NOTES

58       r.out.mat exports a Version 4 MAT-File. These files should successfully
59       load  into  more modern versions of Matlab and Octave without any prob‐
60       lems.
61       Everything should be Endian safe, so the resultant file can  be  simply
62       copied  between  different system architectures without binary transla‐
63       tion.
64       As there is no IEEE value for NaN for integer maps, GRASS's null  value
65       is  used to represent it within these maps. You'll have to do something
66       like this to clean them once the map is loaded into Matlab:
67       Null values in maps containing either floating point  or  double-preci‐
68       sion
69       floating point data should translate into <tt>NaN values as expected.
70       r.out.mat must load the entire map into memory before writing,
71       therefore it might have problems with huge maps.
72       (a 3000x4000 DCELL map uses about 100mb RAM)
73       GRASS  defines  its map bounds at the outer-edge of the bounding cells,
74       not at
75       the coordinates of their centroids. Thus, the following Matlab commands
76       may
77       be used to determine the map's resolution information:
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79           [rows cols] = size(map_data)
80           x_range = map_eastern_edge - map_western_edge
81           y_range = map_northern_edge - map_southern_edge
82           ns_res = y_range/rows
83           ew_res = x_range/cols
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EXAMPLE

87       In Matlab, plot with either:
88       imagesc(map_data), axis equal, axis tight, colorbar
89        or
90       contourf(map_data, 24), axis ij, axis equal, axis tight, colorbar
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TODO

94       Add support for exporting map history, category information, color map,
95       etc.
96       Option to export as a version 5 MAT-File, with map and support informa‐
97       tion stored in a single structured array.
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AUTHOR

106       Hamish Bowman
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108       Department of Marine Science
109       University of Otago
110       New Zealand
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112       Last changed: $Date: 2005-12-12 15:53:40 +0100 (Mon, 12 Dec 2005) $
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114       Full index
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116       © 2003-2008 GRASS Development Team
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120GRASS 6.3.0                                                       r.out.mat(1)