satpy.readers.utils module

Helper functions for satpy readers.

satpy.readers.utils.apply_earthsun_distance_correction(reflectance, utc_date=None)[source]

Correct reflectance data to account for changing Earth-Sun distance.

satpy.readers.utils.apply_rad_correction(data, slope, offset)[source]

Apply GSICS-like correction factors to radiance data.

satpy.readers.utils.bbox(img)[source]

Find the bounding box around nonzero elements in the given array.

Copied from https://stackoverflow.com/a/31402351/5703449 .

Returns

rowmin, rowmax, colmin, colmax

class satpy.readers.utils.generic_open(filename, *args, **kwargs)[source]

Bases: object

Context manager for opening either a regular file or a bzip2 file.

Keep filename and mode.

satpy.readers.utils.get_array_date(scn_data, utc_date=None)[source]

Get start time from a channel data array.

satpy.readers.utils.get_earth_radius(lon, lat, a, b)[source]

Compute radius of the earth ellipsoid at the given longitude and latitude.

Parameters
  • lon – Geodetic longitude (degrees)

  • lat – Geodetic latitude (degrees)

  • a – Semi-major axis of the ellipsoid (meters)

  • b – Semi-minor axis of the ellipsoid (meters)

Returns

Earth Radius (meters)

satpy.readers.utils.get_geostationary_angle_extent(geos_area)[source]

Get the max earth (vs space) viewing angles in x and y.

satpy.readers.utils.get_geostationary_bounding_box(geos_area, nb_points=50)[source]

Get the bbox in lon/lats of the valid pixels inside geos_area.

Parameters
  • geos_area – The geostationary area to analyse.

  • nb_points – Number of points on the polygon

satpy.readers.utils.get_geostationary_mask(area, chunks=None)[source]

Compute a mask of the earth’s shape as seen by a geostationary satellite.

Parameters
Returns

Boolean mask, True inside the earth’s shape, False outside.

satpy.readers.utils.get_sub_area(area, xslice, yslice)[source]

Apply slices to the area_extent and size of the area.

satpy.readers.utils.get_user_calibration_factors(band_name, correction_dict)[source]

Retrieve radiance correction factors from user-supplied dict.

satpy.readers.utils.np2str(value)[source]

Convert an numpy.string_ to str.

Parameters

value (ndarray) – scalar or 1-element numpy array to convert

Raises

ValueError – if value is array larger than 1-element or it is not of type numpy.string_ or it is not a numpy array

satpy.readers.utils.reduce_mda(mda, max_size=100)[source]

Recursively remove arrays with more than max_size elements from the given metadata dictionary.

satpy.readers.utils.remove_earthsun_distance_correction(reflectance, utc_date=None)[source]

Remove the sun-earth distance correction.

class satpy.readers.utils.unzip_context(filename)[source]

Bases: object

Context manager for uncompressing a .bz2 file on the fly.

Uses unzip_file. Removes the uncompressed file on exit of the context manager.

Returns: the filename of the uncompressed file or of the original file if it was not compressed.

Keep original filename.

satpy.readers.utils.unzip_file(filename, prefix=None)[source]

Unzip the file ending with ‘bz2’. Initially with pbzip2 if installed or bz2.

Parameters
  • prefix (str, optional) – If file is one of many segments of data, prefix random filename

  • number. (for correct sorting. This is normally the segment) –

Returns

Temporary filename path for decompressed file or None.