[GRASS-user] Input data format and read multiple files into Grass 6.4.1

R.S. Bhalla rsbhalla at gmail.com
Sun Apr 28 20:34:48 PDT 2013

Hi Szilard,
This is for the last bit of your question, not sure if I understand the 
earlier part of what you were asking.
I've been using a loop written in R (spgrass6) for pulling in multiple 
files, I'm sure you can write an equivalent loop in pygrass. Example for 
vector import below, you should be able to do something similar for 
LiDAR files. Hope this helps.

## Start R from within the GRASS console (I simply launch rstudio so I 
have a nice environment to work in)
## Load the required libraries

## Specify the directory where your data sits

## List out the maps you want
vectlist<-c("map1", "map2", "map3",.....)

## Note that GRASS automatically assigns the input file name to the output.
## Also note that the overwrite flag, you are creating a new grass dataset
## For rasters you'll want to set the region and resolution using 
g.region first.
             flags=c("o", "e", "overwrite"),
   i <- i+1;

On 04/29/2013 07:00 AM, Szilard Albert wrote:
> Hello,
> It is my very first attempt to use Grass. Or any other Gis program for 
> that matter.
> I am trying to read in multiple (hundreds, thousand) LiDAR ascii files 
> into Grass. They contain elevation data.
> I think I have managed one, and I can make a map of elevations, using 
> File, Import Raster Map, Multiple formats using GDAL. The format is as 
> follows:
> ncols         1000
> nrows         1000
> xllcorner     562000.000
> yllcorner     7124000.000
> cellsize      1
> nodata_value  -9999.0
> 108.93 108.92 108.97 108.99 109 109.01...
> ...
> ...
> 1000 lines, 1000 columns, representing 1 sq km with values at every 1 
> m. Files are called
> 572000-7144000_dem_1m.asc
> 572000-7145000_dem_1m.asc
> 572000-7146000_dem_1m.asc
> etc.
> Can this data be loaded as is, or it needs to be converted to a format 
> where
> X Y Z are columns 1, 2, 3 etc..
> My question is, how do Y read in multiple files? I have tried 
> concatenating them, no luck.
> Thank you for your help..
> regards,
> Szilard
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R.S. Bhalla, Ph.D.
Research Associate
Foundation for Ecological Research, Advocacy and Learning (FERAL)
Ph. +91 413 2671566, Fax. +91 413  2671567
Web: http://www.feralindia.org/drupal/users/rs-bhalla

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