[GRASS5] Presence of NULL data in raster maps?

[Andrea Antonello]

On Friday 02 July 2004 23:38, Markus Neteler wrote:
> Hi,
>
> there seems to be missing a function which reports the presence
> of NULL data in a raster map. This functions is needed for
> interfacing GRASS to GDAL, especially for 8 bit data.
> At time the entire map must be scanned, right? 

Yes

> This can become pretty time consuming.
> Is it sufficient to test the presence of the 'null' file
> within this potential function? 

Following the developer's manual yes.
BTW, the null file could be scanned to contain only null-bytes. It's 8 times 
less time consuming... :)

> A bit dirty, but otherwise the 
> cellhd file needed an addition (null: true or whatever).
>
> Suggestions (or code)?

I think the best thing would be to check existence of null file. But I don't 
know exaclty which changes  that would need... hmm...

Cheers
Andrea

>
> Markus
>
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University of Trento
Department of Civil and Environmental Engineering
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Andrea Antonello
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