Writers

SatPy makes it possible to save datasets in multiple formats. For details on additional arguments and features available for a specific Writer see the table below. Most use cases will want to save datasets using the save_datasets() method:

>>> scn.save_datasets(writer='simple_image')

The writer parameter defaults to using the geotiff writer. One common parameter across almost all Writers is filename and base_dir to help automate saving files with custom filenames:

>>> scn.save_datasets(
...     filename='{name}_{start_time:%Y%m%d_%H%M%S}.tif',
...     base_dir='/tmp/my_ouput_dir')

Changed in version 0.10: The file_pattern keyword argument was renamed to filename to match the save_dataset method’s keyword argument.

SatPy Writers
Description Writer name Status
GeoTIFF geotiff Nominal
Simple Image (PNG, JPEG, etc) simple_image Nominal
NinJo TIFF (using pyninjotiff package) ninjotiff Nominal
NetCDF (Standard CF) cf Pre-alpha
AWIPS II Tiled SCMI NetCDF4 scmi Beta

Available Writers

To get a list of available writers use the available_writers function:

>>> from satpy import available_writers
>>> available_writers()

Colorizing and Palettizing using user-supplied colormaps

Note

In the future this functionality will be added to the Scene object.

It is possible to create single channel “composites” that are then colorized using users’ own colormaps. The colormaps are Numpy arrays with shape (num, 3), see the example below how to create the mapping file(s).

This example creates a 2-color colormap, and we interpolate the colors between the defined temperature ranges. Beyond those limits the image clipped to the specified colors.

>>> import numpy as np
>>> from satpy.composites import BWCompositor
>>> from satpy.enhancements import colorize
>>> from satpy.writers import to_image
>>> arr = np.array([[0, 0, 0], [255, 255, 255]])
>>> np.save("/tmp/binary_colormap.npy", arr)
>>> compositor = BWCompositor("test", standard_name="colorized_ir_clouds")
>>> composite = compositor((local_scene[10.8], ))
>>> img = to_image(composite)
>>> kwargs = {"palettes": [{"filename": "/tmp/binary_colormap.npy",
...           "min_value": 223.15, "max_value": 303.15}]}
>>> colorize(img, **kwargs)
>>> img.show()

Similarly it is possible to use discrete values without color interpolation using palettize() instead of colorize().

You can define several colormaps and ranges in the palettes list and they are merged together. See trollimage documentation for more information how colormaps and color ranges are merged.

The above example can be used in enhancements YAML config like this:

hot_or_cold:
  standard_name: hot_or_cold
  operations:
    - name: colorize
      method: &colorizefun !!python/name:satpy.enhancements.colorize ''
      kwargs:
        palettes:
          - {filename: /tmp/binary_colormap.npy, min_value: 223.15, max_value: 303.15}

Saving multiple Scenes in one go

As mentioned earlier, it is possible to save Scene datasets directly using save_datasets() method. However, sometimes it is beneficial to collect more Scenes together and process and save them all at once.

>>> from satpy.writers import compute_writer_results
>>> res1 = scn.save_datasets(filename="/tmp/{name}.png",
...                          writer='simple_image',
...                          compute=False)
>>> res2 = scn.save_datasets(filename="/tmp/{name}.tif",
...                          writer='geotiff',
...                          compute=False)
>>> results = [res1, res2]
>>> compute_writer_results(results)