
 
Hi,
 
I am trying to use the Grid Calculator in SAGA, through RSAGA but I have problems with the parameter FORMUL,
 
I can´t get the function "a/b" works,
 
the functions "a+b", or "a-b", or "a*b" works, but "a/b" does not,
 
Any help is appreciated,
 
see the code below for the errors reported,
 
thanks,
 
Ali Santacruz
M.Sc. Geomatics.
National University of Colombia,
Bogota, Colombia
E-mail: amsantac@unal.edu.co
 
 
## this formula does not work:
> rsaga.geoprocessor("grid_calculus", 1, list(INPUT="dem.sgrd;brillo.sgrd", RESULT="out2", FORMUL="a/b"))C:\Users\geomatica\Desktop>C:\Users\geomatica\Documents\R\win-library\2.6\RSAGA\saga_vc\saga_cmd.exe grid_calculus 1 -silent -INPUT dem.sgrd;brillo.sgrd -RESULT out2 -FORMUL a\b 
SAGA CMD 2.0
Copyright (C) 2005 by Olaf Conradunder GNU General Public License (GPL)library path:   C:/Users/geomatica/Documents/R/win-library/2.6/RSAGA/saga_vc/moduleslibrary name:   grid_calculusmodule name:    Grid Calculator
Load grid: dem.sgrd...
Load grid: brillo.sgrd...
Parameters:[Grid system] Grid system: 0.008462; 1506x 1585y; -79.300459x -4.492490y[Grid list] Grids: 2 objects (dem.sgrd, brillo.sgrd))[Grid] Result: new[Text] Formula: a\bError at character #0 of the function: a\b
 
function not found
error: executing module [Grid Calculator]
 
# this formula does not work either:
> rsaga.geoprocessor("grid_calculus", 1, list(INPUT="dem.sgrd;brillo.sgrd", RESULT="out2", FORMUL="a\b"))
C:\Users\geomatica\Desktop>C:\Users\geomatica\Documents\R\win-library\2.6\RSAGA\saga_vc\saga_cmd.exe grid_calculus 1 -silent -INPUT dem.sgrd;brillo.sgrd -RESULT out2 -FORMUL  
SAGA CMD 2.0
Copyright (C) 2005 by Olaf Conradunder GNU General Public License (GPL)library path:   C:/Users/geomatica/Documents/R/win-library/2.6/RSAGA/saga_vc/moduleslibrary name:   grid_calculusmodule name:    Grid Calculator
Load grid: dem.sgrd...
Load grid: brillo.sgrd...
Parameters:[Grid system] Grid system: 0.008462; 1506x 1585y; -79.300459x -4.492490y[Grid list] Grids: 2 objects (dem.sgrd, brillo.sgrd))[Grid] Result: new[Text] Formula: Error at character #0 of the function: 
 
function not found
error: executing module [Grid Calculator]
 
 
# this formula works:
 
> rsaga.geoprocessor("grid_calculus", 1, list(INPUT="dem.sgrd;brillo.sgrd", RESULT="out2", FORMUL="a+b"))C:\Users\geomatica\Desktop>C:\Users\geomatica\Documents\R\win-library\2.6\RSAGA\saga_vc\saga_cmd.exe grid_calculus 1 -silent -INPUT dem.sgrd;brillo.sgrd -RESULT out2 -FORMUL a+b 
SAGA CMD 2.0
Copyright (C) 2005 by Olaf Conradunder GNU General Public License (GPL)library path:   C:/Users/geomatica/Documents/R/win-library/2.6/RSAGA/saga_vc/moduleslibrary name:   grid_calculusmodule name:    Grid Calculator
Load grid: dem.sgrd...
Load grid: brillo.sgrd...
Parameters:[Grid system] Grid system: 0.008462; 1506x 1585y; -79.300459x -4.492490y[Grid list] Grids: 2 objects (dem.sgrd, brillo.sgrd))[Grid] Result: new[Text] Formula: a+bSave grid: out2...
 
> rsaga.geoprocessor("grid_calculus", 1, list(INPUT="dem.sgrd;brillo.sgrd", RESULT="out2"))C:\Users\geomatica\Desktop>C:\Users\geomatica\Documents\R\win-library\2.6\RSAGA\saga_vc\saga_cmd.exe grid_calculus 1 -silent -INPUT dem.sgrd;brillo.sgrd -RESULT out2 
SAGA CMD 2.0
Copyright (C) 2005 by Olaf Conradunder GNU General Public License (GPL)library path:   C:/Users/geomatica/Documents/R/win-library/2.6/RSAGA/saga_vc/moduleslibrary name:   grid_calculusmodule name:    Grid Calculator
Load grid: dem.sgrd...
Load grid: brillo.sgrd...
Parameters:[Grid system] Grid system: 0.008462; 1506x 1585y; -79.300459x -4.492490y[Grid list] Grids: 2 objects (dem.sgrd, brillo.sgrd))[Grid] Result: new[Text] Formula: (a - b) / (a + b)Save grid: out2...
 
 
> sessionInfo()R version 2.6.1 (2007-11-26) i386-pc-mingw32 
locale:LC_COLLATE=Spanish_Colombia.1252;LC_CTYPE=Spanish_Colombia.1252;LC_MONETARY=Spanish_Colombia.1252;LC_NUMERIC=C;LC_TIME=Spanish_Colombia.1252
attached base packages:[1] stats     graphics  grDevices utils     datasets  methods   base     
other attached packages:[1] RSAGA_0.9-1
loaded via a namespace (and not attached):[1] rcompgen_0.1-17 tools_2.6.1    
 
> From: hengl@science.uva.nl> To: r-sig-geo@stat.math.ethz.ch> Date: Wed, 30 Jan 2008 10:13:55 +0100> Subject: [R-sig-Geo] FYI: Merging GIS and statistics --- RSAGA> > > > Dear all,> > I just started running analysis with the RSAGA package> (http://cran.r-project.org/src/contrib/Descriptions/RSAGA.html), i.e. the R scripting link to SAGA> GIS (by Olaf Conrad and colleagues, over 120 modules), that was suggested to me by Paulo van Breugel> and I think that this could really be the missing link between statistics and GIS. My experiences so> far are very positive --- especially if you work with large grids, because SAGA is quite fast for> calculations. Here are some examples from Geomorphometry / Digital Soil Mapping:> > 0. Getting started:> > ****************************************************************************> # Download the SAGA 2.0.1 binaries (http://sourceforge.net/projects/saga-gis/) and unzip them to a> local directory e.g. "C:/Progra~1/saga_vc"; # Start R and install the RSAGA package; # load the> library and set the directory where the SAGA binaries sit:> > library(RSAGA)> rsaga.env(path="C:/Progra~1/saga_vc")> > # To get the exact names of parameters look for a name in the "/modules" directory and then use:> > rsaga.get.modules("geostatistics_kriging")> rsaga.get.usage("geostatistics_kriging", 2)> > ****************************************************************************> > 1. Error propagation and geomorphometry (both can be run via R now):> > ****************************************************************************> > # Import the point measurements of heights to generate a DEM:> > elevations <- read.delim("elevations.txt") coordinates(elevations)=~X+Y> spplot(elevations)> > # Import the grid definition:> > gridmaps = readGDAL("SMU1.asc")> gridmaps$SMU1 = gridmaps$band1> > # Derive area in km^2:> > maparea => (gridmaps@bbox["x","max"]-gridmaps@bbox["x","min"])*(gridmaps@bbox["y","max"]-gridmaps@bbox["y","min> "])/1e+06> > # Fit a variogram for elevations and produce 50 realizations of a DEM using Sequential Gaussian> Simulations:> > elevations.or = variogram(Z~1, elevations) > elevations.ovgm = fit.variogram(elevations.or, vgm(1, "Sph", 1000, 1)) > plot(elevations.or, elevations.ovgm, plot.nu=F, pch="+")> > DEM.sim = krige(Z~1, elevations, gridmaps, elevations.ovgm, nmax=40, nsim=50)> > # Visualize the simulated DEMs in R:> > for (i in 1:length(DEM.sim@data)) {> image(as.image.SpatialGridDataFrame(DEM.sim[i]), col=terrain.colors(16), asp=1) }> > # Write the simulated DEMs in ArcInfo ASCII format:> > for (i in 1:length(DEM.sim@data)) {> write.asciigrid(DEM.sim[i], c(paste("DEM",as.character(i),".asc",sep="")))> }> > # Now, derive SLOPE maps in SAGA 50 times:> # ESRI wrapper is used to get the maps directly in ArcInfo ASCII format;> > for (i in 1:length(DEM.sim@data)) {> rsaga.esri.wrapper(rsaga.slope, method="poly2zevenbergen",> in.dem=c(paste("DEM",as.character(i),sep="")), out.slope=c(paste("SLOPE",as.character(i),sep="")),> prec=3, condensed.res=FALSE, intern=FALSE, show.output.on.console=FALSE) }> > # Optional: generate a DEM using the Thin Plate Spline (local) interpolation in SAGA:> > writeOGR(elevations, "elevations.shp", "elevations", "ESRI Shapefile") > > rsaga.get.usage("grid_spline", 1) rsaga.geoprocessor(lib="grid_spline", module=1,> param=list(GRID="DEMtps.sgrd", SHAPES="elevations.shp", FIELD=1, RADIUS=sqrt(maparea)*1000/3,> SELECT=1, MAXPOINTS=30, TARGET=2, GRID_GRID="DEM1.sgrd")) rsaga.sgrd.to.esri(in.sgrds="DEMtps.sgrd",> out.grids="DEMtps.asc", out.path="D:/GEOSTAT/maps/RSAGA", prec=1)> > > ****************************************************************************> > 2. Spatial interpolation > Especially suitable for large maps (R+gstat often fail due to memory limit problems):> > ****************************************************************************> # Export the predictors to SAGA format:> > predict.list = gl(n=9, k=1,> labels=c("DEM","SLOPE","PLANC","TWI","SINS","SMU1","SMU3","SMU4","SMU9"))> rsaga.esri.to.sgrd(in.grids=levels(predict.list),> out.sgrds=set.file.extension(levels(predict.list),".sgrd"), in.path="D:/GEOSTAT/maps/RSAGA")> > # predict values in SAGA using only regression model:> > rsaga.get.usage("geostatistics_grid", 4) rsaga.geoprocessor(lib="geostatistics_grid", module=4,> param=list(GRIDS="DEM.sgrd;SLOPE.sgrd;PLANC.sgrd;TWI.sgrd;SINS.sgrd;SMU1.sgrd;SMU3.sgrd;SMU4.sgrd;SM> U9.sgrd", SHAPES="baranja.shp", ATTRIBUTE=0, TABLE="regout.dbf", RESIDUAL="solum_res.shp",> REGRESSION="SOLUM_reg.sgrd", INTERPOL=0))> > # Ordinary kriging:> > rsaga.get.usage("geostatistics_kriging", 1) rsaga.geoprocessor(lib="geostatistics_kriging",> module=1, param=list(GRID="SOLUM_ok.sgrd", VARIANCE="SOLUM_okvar.sgrd", SHAPES="baranja.shp",> FIELD=0, MODEL=1, NUGGET=0, SILL=200, RANGE=500, TARGET=2, GRID_GRID="SLOPE.sgrd"))> > # Regression-kriging:> > rsaga.get.usage("geostatistics_kriging", 3) rsaga.geoprocessor(lib="geostatistics_kriging",> module=3,> param=list(GRIDS="DEM.sgrd;SLOPE.sgrd;PLANC.sgrd;TWI.sgrd;SINS.sgrd;SMU1.sgrd;SMU3.sgrd;SMU4.sgrd;SM> U9.sgrd", GRID="SOLUM_rk.sgrd", SHAPES="baranja.shp", FIELD=0, MODEL=1, NUGGET=0, SILL=200,> RANGE=500, INTERPOL=0)) > # Does not work yet. Possibly a bug in the saga_cmd.exe?> > ****************************************************************************> > The complete script and datasets are available at:> > http://spatial-analyst.net/GRK/examplesRSAGA.zip (400 KB)> > So the only real problem is the import/export from R to SAGA, which I guess could be solved very> easily if the next version of rgdal would support SAGA format.> > > Tom Hengl> http://spatial-analyst.net> > _______________________________________________> R-sig-Geo mailing list> R-sig-Geo@stat.math.ethz.ch> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
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