Hi,
this...
> for (i in length(asc.files[i])) {
...only works if the variable i existed previously, and it seems that
its value happened to be 1 in your case. It then counts from
length(asc.files[i]) to length(asc.files[i]); asc.files[i] is a vector
of length one (because i is 1), so the for loop goes from i=1 to i=1.
This is what you want to do:
> for (i in 1:length(asc.files)) {
Cheers
Alex
Tim Sippel wrote:
Hi Alex-
Thanks for the response, which helped me get a step closer to what I want.
Now that I have removed the extensions from the files as you suggest, I am
able to process one file, but am not able to process an entire directory of
files. Upon running a loop over all files in the directory, it only
processes the first file and returns the calculated values (slope in my
case). However, there are 62 files in my directory and I'm at a loss for
why I can't process all of them in my loop. Sample code follows:
library(RSAGA)
wd.in<-"C:\\my.dir"
setwd(wd.in)
env<-rsaga.env(path="C:\\programs\\saga_vc", cmd="saga_cmd.exe")
asc.files<-dir(wd.in, pattern='.asc$')
asc.files<-substr(basename(asc.files), 1, nchar(basename(asc.files)) - 4)
asc.files
[1] "tmp1_220E-15N2005-03-02" "tmp10_220E-15N2005-05-13"
"tmp100_220E-15N2007-05-13" "tmp101_220E-15N2007-05-21"
"tmp102_220E-15N2007-05-29"
for (i in length(asc.files[i])) {
rsaga.esri.wrapper(fun=rsaga.slope, in.dem=asc.files[i],
method="maxslope", in.esri=T, out.esri=T, clean.up=T,
out.slope=c(paste("SLOPE",asc.files[i],sep="")), env=env, esri.workspace=
wd.in, format="ascii", georef="corner", prec=3)
}
This loop works, but only processes one file and stops. My directory now
includes the following files:
[1] "SLOPEtmp1_220E-15N2005-03-02" "tmp1_220E-15N2005-03-02"
"tmp10_220E-15N2005-05-13" "tmp100_220E-15N2007-05-13"
Thanks again for suggestions on how to process the whole directory.
Tim Sippel
On Mon, Mar 2, 2009 at 4:43 AM, Alexander Brenning <brenn...@uwaterloo.ca>wrote:
Hi Tim,
the rsaga.esri.wrapper currently expects the in.* and out.* arguments (with
the ASCII/float ESRI grids) to have NO file extension - the file extension
to be used for all ESRI grids can be given by the esri.extension argument;
it currently defaults to ".asc" when format="ascii" and to ".flt" when
format="binary". (Sorry that the help file is not explicit enough regarding
the file extensions; will add this to the next update.)
Two more remarks on your code:
read.ascii.grid(i)
This simply reads the grid but does nothing else - redundant.
prec=1
Slope is calculated in radians (see ?rsaga.slope). So with a 0.1 radian
increment (the smallest increment that can be represented with prec=1
digits) you get 0.1 * 180 / pi = 5.7 degree increments on the degree scale -
you probably want to haver a finer discretization. I would recommend prec=3
in the case of slope (and probably prec=6 or 7 for curvature attributes).
I hope this helps.
Cheers
Alex
Tim Sippel wrote:
I'm using RSAGA (version 0.9-4) to calculate rate of change (slope) on a
series of .asc files. I'm getting en error message saying it can't open
the
grid. My code follows:
library(RSAGA)
# data directory containing my .asc files to calculate slope on
wd.in<-"C:\\my.data.dir"
setwd(wd.in)
env<-rsaga.env(path="C:\\programs\\saga_vc", cmd="saga_cmd.exe")
asc.list<-dir(wd.in, pattern='.asc$')
for (i in asc.list) {
read.ascii.grid(i)
rsaga.esri.wrapper(fun=rsaga.slope, in.dem=i, method="maxslope",
in.esri=T, out.esri=T, clean.up=T,
out.slope=c(paste("SLOPE",as.character(i),sep="")), env=env,
esri.workspace=wd.in, format="ascii", georef="corner", prec=1)
}
Here are some of the data files in my directory from my asc.list object
above:
asc.list
[1] "tmp1_220E-15N2005-03-02.asc" "tmp10_220E-15N2005-05-13.asc"
"tmp100_220E-15N2007-05-13.asc" "tmp101_220E-15N2007-05-21.asc"
[5] "tmp102_220E-15N2007-05-29.asc" "tmp103_220E-15N2007-06-06.asc"
"tmp104_220E-15N2007-06-14.asc" "tmp105_220E-15N2007-06-22.asc"
The error I'm getting is below:
SAGA CMD 2.0.3
library path: C:\programs\saga_vc/modules
library name: ta_morphometry
module name : Local Morphometry
author : (c) 2001 by O.Conrad
Load grid: tmp1_220E-15N2005-03-02.asc...
failed
error: Grid file could not be opened.
error: input file [tmp1_220E-15N2005-03-02.asc]
error: executing module [Local Morphometry]
Not sure what I've done wrong in calling in the grid files and would
appreciate advice.
Best regards,
Tim Sippel
University of Auckland
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--
Alexander Brenning
brenn...@uwaterloo.ca - T +1-519-888-4567 ext 35783
Department of Geography and Environmental Management
University of Waterloo
200 University Ave. W - Waterloo, ON - Canada N2L 3G1
http://www.fes.uwaterloo.ca/geography/faculty/brenning/
--
Alexander Brenning
brenn...@uwaterloo.ca - T +1-519-888-4567 ext 35783
Department of Geography and Environmental Management
University of Waterloo
200 University Ave. W - Waterloo, ON - Canada N2L 3G1
http://www.fes.uwaterloo.ca/geography/faculty/brenning/
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