variable from python to composite

[gersmit]

Is it possible to use an varaibale in Python to use in generic.yaml composite.
For example:
colorized_ir_clouds:
standard_name: colorized_ir_clouds
operations:
- name: colorize
method: !!python/name:satpy.enhancements.colorize
kwargs:
palettes:
- {colors: rainbow, min_value: 190.15, max_value: 310.14}
- {colors: blues, min_value: 310.15, max_value: 350.15}

Is it possible to use a variable in Python that change the min_value and max_value of the palettes -> colors from the script.
When yes, can you tell me how to handle.

[djhoese]

Not really. The information in the YAML is meant to be static (unchanging). You could convert your DataArray to an image and do the enhancement yourself. Something like this:

scn = Scene(...)
# load some channels and do some resampling...or whatever

from satpy.writers import to_image
from trollimage.colormaps import rainbow, blues

rainbow.set_range(190.15, 310.14)
blues.set_range(310.15, 350.15)
my_cmap = rainbow + blues

img = to_image(scn['my_channel'])
img.colorize(my_cmap)

scn['my_channel'] = img.data
scn.save_datasets(enhance=False)

We set enhance=False so that Satpy doesn't try to re-enhance the data. I'm 80% sure the above should work.

[gersmit]

@djhoese work perfect, see image when i do img.show()
Only one small error, the save_datasets works normaly good.
Now i get error on save_datasets:
Traceback (most recent call last):
File "/home/pi/a-satpy-testen/cursus2_seviri.py", line 241, in
local_scn.save_datasets(enhance=False)
File "/home/pi/.local/lib/python3.7/site-packages/xarray/core/common.py", line 229, in getattr
"{!r} object has no attribute {!r}".format(type(self).name, name)
AttributeError: 'DataArray' object has no attribute 'save_datasets'

[djhoese]

Double check what you did with local_scn. You probably did local_scn = img.data but you were supposed to do the equivalent of local_scn['my_channel'] = img.data.

[gersmit]

@djhoese thanks, I did both, now again as you say
Error =
Traceback (most recent call last):
File "rasterio/_crs.pyx", line 253, in rasterio._crs._CRS.from_dict
File "rasterio/_err.pyx", line 194, in rasterio._err.exc_wrap_ogrerr
rasterio._err.CPLE_BaseError: OGR Error code 7

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/home/pi/a-satpy-testen/cursus2_seviri.py", line 242, in
local_scn.save_datasets(enhance=False)
File "/home/pi/.local/lib/python3.7/site-packages/satpy/scene.py", line 1368, in save_datasets
return writer.save_datasets(datasets, compute=compute, **save_kwargs)
File "/home/pi/.local/lib/python3.7/site-packages/satpy/writers/init.py", line 697, in save_datasets
results.append(self.save_dataset(ds, compute=False, **kwargs))
File "/home/pi/.local/lib/python3.7/site-packages/satpy/writers/init.py", line 829, in save_dataset
return self.save_image(img, filename=filename, compute=compute, fill_value=fill_value, **kwargs)
File "/home/pi/.local/lib/python3.7/site-packages/satpy/writers/geotiff.py", line 219, in save_image
**gdal_options)
File "/home/pi/.local/lib/python3.7/site-packages/trollimage/xrimage.py", line 422, in save
**format_kwargs)
File "/home/pi/.local/lib/python3.7/site-packages/trollimage/xrimage.py", line 517, in rio_save
crs = rasterio.crs.CRS(data.attrs['area'].proj_dict)
File "/usr/lib/python3/dist-packages/rasterio/crs.py", line 70, in init
self._crs = _CRS.from_dict(data)
File "rasterio/_crs.pyx", line 255, in rasterio._crs._CRS.from_dict
rasterio.errors.CRSError: The PROJ4 dict could not be understood. OGR Error code 7

[gersmit]

@djhoese I have it now and is looking good, thanks for sofar

local_scn['my_channel'] = img.data
color_transp = 'my_channel'
img.show()
local_scn.save_dataset(color_transp, writer='simple_image',
enhance=False, # zonder maakt kleur harder
filename='/home/pi/a-satpy-testen/images/'+ file_name + 'color_scn.png',
overlay={'coast_dir': '/home/pi/a-satpy-testen/GSHHS_DATA_ROOT/',
'overlays': {'grid': grid,
'coasts': coast,
'borders': borders,
'rivers': rivers
}})

[djhoese]

Sounds like you were able to make it work. If so, I'm going to close this. If not, please comment and we can reopen this.