[gdal-dev] python: setting nodata affects all bands

[Frank Warmerdam]

Matt Wilkie wrote:
> Hi Folks,
> 
> I'm endeavouring to teach myself a little about pythin and gdal by 
> working on a python script to set the nodata value on a raster. I've 
> encountered a puzzling thing and I don't know if this is expected 
> behaviour or I'm doing something wrong. If set nodata on a single band, 
> all of the bands are affected. For my current project this doesn't 
> matter, but it just doesn't seem right to me.
> 
> In the script below I expected band 1 to be changed and the others to 
> remain as they are.

Matt,

Conceptually each band has a distinct no data value.  However, in
practice, some drivers assume a common nodata value for all bands.  Was
this possibly a geotiff file you were operating on?  This could be
construed as a bug or at least a deficiency of the format driver you
were using.

Best regards,
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