pyresample.utils package

Submodules

pyresample.utils.cartopy module

Classes for geometry operations

pyresample.utils.cartopy.from_proj(proj4_terms, globe=None, bounds=None)

Not-as-good version of cartopy’s ‘from_proj’ function.

The user doesn’t have a newer version of Cartopy so there is no from_proj function to use which does a fancier job of creating CRS objects from PROJ.4 strings than this does.

pyresample.utils.cf module

Load an AreaDefinition object from a netCDF/CF file.

pyresample.utils.cf.load_cf_area(nc_file, variable=None, y=None, x=None)

Load an AreaDefinition object from a netCDF/CF file.

Parameters

  • nc_file (string or object) – path to a netCDF/CF file, or opened xarray.Dataset object

  • variable (string, optional) – name of the variable to load the AreaDefinition from. If the variable is not a CF grid_mapping container variable, it should be a variable having a :grid_mapping attribute. If variable is None the file will be searched for valid CF area definitions

  • y (string, optional) – name of the variable to use as ‘y’ axis of the CF area definition If y is None an appropriate ‘y’ axis will be deduced from the CF file

  • x (string, optional) – name of the variable to use as ‘x’ axis of the CF area definition If x is None an appropriate ‘x’ axis will be deduced from the CF file

Returns

are_def, cf_info – cf_info holds info about how the AreaDefinition was defined in the CF file.

Return type

geometry.AreaDefinition object, dict

pyresample.utils.proj4 module

pyresample.utils.proj4.convert_proj_floats(proj_pairs)

Convert PROJ.4 parameters to floats if possible.

pyresample.utils.proj4.proj4_dict_to_str(proj4_dict, sort=False)

Convert a dictionary of PROJ.4 parameters to a valid PROJ.4 string

pyresample.utils.proj4.proj4_radius_parameters(proj4_dict)

Calculate ‘a’ and ‘b’ radius parameters.

Parameters

proj4_dict (str or dict) – PROJ.4 parameters

Returns

equatorial and polar radius

Return type

a (float), b (float)

pyresample.utils.proj4.proj4_str_to_dict(proj4_str)

Convert PROJ.4 compatible string definition to dict

EPSG codes should be provided as “EPSG:XXXX” where “XXXX” is the EPSG number code. It can also be provided as "+init=EPSG:XXXX" as long as the underlying PROJ library supports it (deprecated in PROJ 6.0+).

Note: Key only parameters will be assigned a value of True.

pyresample.utils.rasterio module

pyresample.utils.rasterio.get_area_def_from_raster(source, area_id=None, name=None, proj_id=None, proj_dict=None)

Construct AreaDefinition object from raster.

Parameters

  • source (str, Dataset, DatasetReader or DatasetWriter) – A file name. Also it can be osgeo.gdal.Dataset, rasterio.io.DatasetReader or rasterio.io.DatasetWriter

  • area_id (str, optional) – ID of area

  • name (str, optional) – Name of area

  • proj_id (str, optional) – ID of projection

  • proj_dict (dict, optional) – PROJ.4 parameters

Returns

area_def – AreaDefinition object

Return type

object

Module contents

Miscellaneous utility functions for pyresample.

pyresample.utils.check_and_wrap(lons, lats)

Wrap longitude to [-180:+180[ and check latitude for validity.

Parameters

  • lons (ndarray) – Longitude degrees

  • lats (ndarray) – Latitude degrees

Returns

Longitude degrees in the range [-180:180[ and the original

latitude array

Return type

lons, lats

Raises

ValueError – If latitude array is not between -90 and 90

pyresample.utils.check_slice_orientation(sli)

Check that the slice is slicing the right way.

pyresample.utils.convert_def_to_yaml(*args, **kwargs)
pyresample.utils.create_area_def(*args, **kwargs)
pyresample.utils.fwhm2sigma(fwhm)

Calculate sigma for gauss function from FWHM (3 dB level)

Parameters

fwhm (float) – FWHM of gauss function (3 dB level of beam footprint)

Returns

sigma – sigma for use in resampling gauss function

Return type

float

pyresample.utils.generate_nearest_neighbour_linesample_arrays(source_area_def, target_area_def, radius_of_influence, nprocs=1)

Generate linesample arrays for nearest neighbour grid resampling

Parameters

  • source_area_def (object) – Source area definition as geometry definition object

  • target_area_def (object) – Target area definition as geometry definition object

  • radius_of_influence (float) – Cut off distance in meters

  • nprocs (int, optional) – Number of processor cores to be used

Returns

(row_indices, col_indices)

Return type

tuple of numpy arrays

pyresample.utils.generate_quick_linesample_arrays(source_area_def, target_area_def, nprocs=1)

Generate linesample arrays for quick grid resampling

Parameters

  • source_area_def (object) – Source area definition as geometry definition object

  • target_area_def (object) – Target area definition as geometry definition object

  • nprocs (int, optional) – Number of processor cores to be used

Returns

(row_indices, col_indices)

Return type

tuple of numpy arrays

pyresample.utils.get_area_def(*args, **kwargs)
pyresample.utils.is_pyproj2()

Determine whether the current pyproj version is >= 2.0

pyresample.utils.load_area(*args, **kwargs)
pyresample.utils.parse_area_file(*args, **kwargs)
pyresample.utils.recursive_dict_update(d, u)

Recursive dictionary update using

Copied from:

pyresample.utils.wrap_longitudes(lons)

Wrap longitudes to the [-180:+180[ validity range (preserves dtype)

Parameters

lons (numpy array) – Longitudes in degrees

Returns

lons – Longitudes wrapped into [-180:+180[ validity range

Return type

numpy array