Hi! I wonder if anyone could explain to me how to create a new map (raster) from two pre-existing maps, in mapcalc. Because I have problems with understanding how to do this in r.mapcalc
I have two raster datasets that I would like to combine like so; if the cell is in map a, assign the value 7; if it is in map B, assign the correct value from B, (i.e keep the value the cell already have in B). I have tried to read "Performing Map Calculations on GRASS Data: r.mapcalc Program Tutorial", by Marji Larson, Michael Shapiro and Scott Tweddale, U.S. Army Construction Engineering Research Laboratory (December 1991) , and they give this example: MAPCALC> aspect.str = if(streams,26,aspect) This should then give a new map that contains the values from "aspect", but with the value 26 assigned to cells with "streams". Example from my experiments: R_test9 = if([EMAIL PROTECTED] == 1,7, [EMAIL PROTECTED] ) This makes a new map; but it contains only 7, were there was data in R_vannA, and else, NULL (I guess), see otput below of r.info. I also tried "R_test9 = if(if([EMAIL PROTECTED] == 1),7, [EMAIL PROTECTED] ) ; and this gives the same (non) result. And "R_test10 = if([EMAIL PROTECTED], 7, [EMAIL PROTECTED])"; also the same as; I.E not what I wanted. The problem is that it never assigns a value from [EMAIL PROTECTED] What am I missing? Or doing wrong? Regards Larsf Running; SUSE 10.3, grass63 dated 12.09 from http://download.opensuse.org/repositories/Application:/Geo/openSUSE_10.3/i586/ ---------------------------------------------r.info output (example) > (3) r.info [EMAIL PROTECTED] > > +-------------------------------------------------------------------------- >--+ > > | Layer: [EMAIL PROTECTED] Date: Sun Sep 21 15:28:36 > 2008 > | | Mapset: larsf Login of Creator: larsf > | | Location: Frosta > | | DataBase: /home/larsf/grassgis > | | Title: ( R_test9 ) > | | Timestamp: none > | | > | ------------------------------------------------------------------------ > |----| > | > | Type of Map: raster Number of Categories: 7 > | | Data Type: CELL > | | Rows: 3360 > | | Columns: 3720 > | | Total Cells: 12499200 > | | Projection: UTM (zone 32) > | | N: 7062800 S: 7046000 Res: 5 > | | E: 596600 W: 578000 Res: 5 | > | Range of data: min = 7 max = 7 > | | > | > | Data Description: > | | generated by r.mapcalc > | | > | > | Comments: > | | if([EMAIL PROTECTED] == 1, 7, [EMAIL PROTECTED]) > > | | > > > +-------------------------------------------------------------------------- >--+ _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
