[GRASS-dev] Rast_open_new_null()

[Markus Metz]

On Tue, May 28, 2013 at 5:38 AM, Yann Chemin <ychemin at gmail.com> wrote:
> Hi,
>
> is there a small way to open a new file and set all values to NULL?
> The function would be something like Rast_open_new_null(),

Using a module:
r.mapcalc "newmap = null()"

Using C code:

int row, nrows;
int data_type;
void *buf;

data_type = <one of CELL_TYPE, FCELL_TYPE, DCELL_TYPE>

/* open raster map ... */

buf = Rast_allocate_buf(data_type);

Rast_set_null_value(buf, Rast_window_cols(), data_type);

nrows = Rast_window_rows();

for (row = 0; row < nrows; row++) {
    Rast_put_row(buf, data_type);
}

/* close raster map ... */

Markus M