pylawr.functions.grid#

pylawr.functions.grid.get_cartesian(grid, use_altitude=False)[source]#

This method calculates cartesian coordinates based on the given grid. The cartesian coordinates are calculated based on simplifications and uses trigonometric functions. The latitude (lat), longitude (lon) and height values (h) are extracted from the given grid, while the earth_radius (R) is set for the remapping.

..math:

x = R * cos(lat) * cos(lon)

y = R * cos(lat) * sin(lon)

z = h + R * sin(lat)
Parameters

  • grid (child of pylawr.grid.BaseGrid) – The cartesian coordinates are calculated based on this grid. The grid needs the methods: get_altitude() and get_lat_lon() and should be a child of BaseGrid.

  • use_altitude (bool) – Use the altitude for cartesian coordinates. Default is False. Note, using the correct altitude for the cartesian coordinates for remapping may not preferred.

Returns

cartesian – The calculated coordinates based on the given grid. The last dimension is x, y and z, while the other dimension sizes are defined by the shape of the input grid.

Return type

xarray.DataArray

pylawr.functions.grid.get_latlon_grid(orig_grid)[source]#

This function can be used to get a rectangular LatLonGrid. The edges of the rectangular grid are determined by the boundary values of the original grid. The median step-wide of the original grid is used as resolution.

Parameters

orig_grid (child of pylawr.grid.BaseGrid) – This original grid is used to determine edges and step wide of the latitude and longitude grid.

Returns

latlon_grid – This grid is created based on given original grid with edges and step wide determined by the original grid.

Return type

pylawr.grid.latlon.LatLonGrid

pylawr.functions.grid.get_masked_grid(origin_grid, mask_array)[source]#

Mask value within a given origin grid.

Parameters

  • mask_array (numpy.ndarray (bool)) – This mask is applied on given origin_grid. Should have the same shape as origin_grid. All values set to True are used, while values set to False are dismissed.

  • origin_grid (child of pylawr.grid.base.BaseGrid) – This grid is used to infer the latitude, longitude and altitude values for the unstructured grid.

Returns

masked_grid – The unstructured grid with all non-masked values. This unstructured grid gets its latitude, longitude and altitude values from given origin_grid. All values set to True within mask_array are used.

Return type

pylawr.grid.unstructured.UnstructuredGrid

pylawr.functions.grid.prepare_grid(grid)[source]#

This method is used to prepare the grid for the remapping, the grid is transformed into cartesian coordinates with :py:meth:_get_cartesian and then stacked and transposed.

Parameters

grid (child of pylawr.grid.BaseGrid) – The cartesian coordinates are calculated based on this grid. The grid needs the methods: get_altitude() and get_lat_lon() and should be a child of BaseGrid.

Returns

cartesian – The calculated coordinates based on the given grid. The last dimension is x, y and z, while the first dimension is a stacked dimension based on the original grid dimensions.

Return type

xarray.DataArray

pylawr.functions.grid.remap_data(data, orig_grid, new_grid, remapper=None)[source]#

This function remaps data based on given grids with given remap instance. If the remap instance was not fitted yet, it will be fitted.

Parameters

  • data (xarray.DataArray) – This data is remapped by given remapper. The last coordinate(s) should be the grid coordinates.

  • orig_grid (child of pylawr.grid.BaseGrid) – This grid is used as basis grid for the remapping. The last data coordinates should have the same shape as this grid.

  • new_grid (child of pylawr.grid.BaseGrid) – The data is remapped to this grid.

  • remapper (child of pylawr.remap.BaseRemap or None, optional) – This remapper is used to remap given data to new grid. If the remapper is already fitted, it is assumed that the remapper was fitted to given grids. Default value (None) is an unfitted NearestNeighbor instance with a single nearest neighbor.

Returns

  • remapped_data (xarray.DataArray) – This data was remapped to new_grid with given remapper.

  • remapper (child of pylawr.remap.BaseRemap) – This remapper was used to remap given data. This remapper is fitted to given grids.

Warning

For a fitted remapper, we assume that the remapper was fitted to given grids!

Notes

Most of processing time is spend on fitting given remapper. It is recommended to give a fitted remapper to increase the speed of this function.