[GRASS-user] changing raster values in r.example

GRASS GRASS user
1

Hi.
I'm starting to write a simple program based on r.example.
For now the goal is to read a DEM file, change some values, and write out another DEM file with the changed values.

The r.example creates the second DEM file but with the default region (how can I change the region?) and does nothing to the values.
So, I tried this:

//********
for (row = 100; row < 200; row++)
  {
    if (G_get_raster_row(infd, inrast, row, data_type) < 0)
      G_fatal_error(_("Unable to read raster map <%s> row %d"), name, row);

    for (col = 240; col < 350; col++) {
      ((CELL *) outrast)[col] = 2000;
    }
  
    if( G_put_raster_row(outfd, outrast, data_type) < 0 ) {
      G_fatal_error(_("Failed writing raster map <%s>"), result);
    }
  }
//********

But it's not writing the changed values.
I even tried changing the r.example as little as possible just changing this function:

//********
CELL c_calc(CELL x)
{
    x = x + 2000;
    return x;
}
//********

But still didn't work. Any clues why it's not writing?
Thanks

2

On Thu, Jun 27, 2013 at 4:50 PM, Pedro Mendonça <pfmendonca@fc.ul.pt> wrote:

Hi.
I'm starting to write a simple program based on r.example.
For now the goal is to read a DEM file, change some values, and write out another DEM file with the changed values.

The r.example creates the second DEM file but with the default region (how can I change the region?) and does nothing to the values.
So, I tried this:

//********

this

for (row = 100; row < 200; row++)
        {

must be

    for (row = 0; row < nrows; row++) {

Otherwise the result will be an incomplete raster map. Did you get any
warnings or errors when executing your module?

Markus M

                if (G_get_raster_row(infd, inrast, row, data_type) < 0)
                        G_fatal_error(_("Unable to read raster map <%s> row %d"), name, row);

                for (col = 240; col < 350; col++) {
                        ((CELL *) outrast)[col] = 2000;
                }

                if( G_put_raster_row(outfd, outrast, data_type) < 0 ) {
                        G_fatal_error(_("Failed writing raster map <%s>"), result);
                }
        }
//********

But it's not writing the changed values.
I even tried changing the r.example as little as possible just changing this function:

//********
CELL c_calc(CELL x)
{
    x = x + 2000;
    return x;
}
//********

But still didn't work. Any clues why it's not writing?
Thanks
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