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Hi Gaspar, <BR>
<BR>
r.mapcalc "new.map = if(flat_map==0.0234,flat_map,null())" -> if you want to preserve original values<BR>
<BR>
or <BR>
<BR>
r.mapcalc "new.map = if(flat_map==0.0234,1,null())" -> if you prefer to assign a value of 1 to those values equal to 0.0234 in the original raster map<BR>
<BR>
It should work.<BR>
Lluís<BR>
<BR>
<BR>
El dc 13 de 04 de 2011 a les 18:21 -0500, en/na Gaspar Reyes Póndigo va escriure:<BR>
<BLOCKQUOTE TYPE=CITE>
Thanks Markus.<BR>
<BR>
I did test with r.mapcalc novo_raster = if"(mi flat_map==0.0234)", but the map is not appropiate. I know the area of value (0.0234), but is not is equal in the novo_raster.<BR>
<BR>
<BR>
El 13/04/2011, a las 17:27, Markus Neteler escribió:<BR>
<BR>
<BLOCKQUOTE TYPE=CITE>
2011/4/13 Gaspar Reyes Póndigo <<A HREF="mailto:gos47@hotmail.com">gos47@hotmail.com</A>>:<BR>
<BLOCKQUOTE TYPE=CITE>
Hello, Dear grass_user. My first forum participation in the grass_user list<BR>
email.<BR>
</BLOCKQUOTE>
<BR>
Welcome!<BR>
<BR>
<BLOCKQUOTE TYPE=CITE>
How to extract values of map raster with r.mapcalc? I need make new map<BR>
raster based on specific value of other raster.<BR>
</BLOCKQUOTE>
<BR>
Please take a look at the if() conditions:<BR>
<BR>
<A HREF="http://grass.osgeo.org/grass64/manuals/html64_user/r.mapcalc.html">http://grass.osgeo.org/grass64/manuals/html64_user/r.mapcalc.html</A><BR>
<BR>
Therein is also a section EXAMPLES.<BR>
<BR>
Markus<BR>
<BR>
</BLOCKQUOTE>
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