[GRASS-user] error while using i.segment.stats

[Moritz Lennert]

Hi Vero,

Le Mon, 2 Dec 2019 13:43:30 +0100,
Veronica Andreo <veroandreo at gmail.com> a écrit :

> Hi,
> 
> We are trying to use i.segment.stats for a map with 800000+ segments
> and already in two different laptops, we get:
> 
> bands=`g.list rast pat=IGUAZU_IMG_* sep=,`
> RASTER_STATS=(min,max,range,mean,stddev,median,first_quart,third_quart,perc_90)
> AREA_STATS=(area,perimeter,compact_circle,compact_square,fd)
> 
> i.segment.stats -rc \
>                  map=segments_full_region \
>                  rasters=$bands \
>                  raster_statistics=$RASTER_STATS \
>                  area_measures=$AREA_STATS \
>                  vectormap=segs_stats_map \
>                  processes=4
> Calculating geometry statistics...
> Calculating statistics for raster maps...
> Exception in thread Thread-3:
> Traceback (most recent call last):
>   File "/usr/lib/python3.6/threading.py", line 916, in
> _bootstrap_inner self.run()
>   File "/usr/lib/python3.6/threading.py", line 864, in run
>     self._target(*self._args, **self._kwargs)
>   File "/usr/lib/python3.6/multiprocessing/pool.py", line 463, in
> _handle_results
>     task = get()
>   File "/usr/lib/python3.6/multiprocessing/connection.py", line 251,
> in recv return _ForkingPickler.loads(buf.getbuffer())
> TypeError: __init__() missing 3 required positional arguments:
> 'module', 'code', and 'returncode'
> 
> Does it have to do with memory? I used the module a month ago with
> 500000+ segments and it worked just fine...

I don't think memory is the issue, but I find the error message
pretty cryptic, so wouldn't exclude altogether. Could it be some
difference between Python 2 and 3 in the multiprocessing module ? Would
it be possible for you try running it in Python 2 ?

Maybe you could also try to run it on a smaller subset of the
segmentation result ?

Moritz


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