API reference¶

Here we will add the documentation for selected modules.

Grid¶

Grid A structured grid on a map projection.

Grid attributes¶

`Grid.proj`	`pyproj.Proj` instance defining the grid’s map projection.
`Grid.nx`	number of grid points in the x direction.
`Grid.ny`	number of grid points in the y direction.
`Grid.dx`	x grid spacing (always positive).
`Grid.dy`	y grid spacing (positive if ll_corner, negative if ul_corner).
`Grid.x0`	X reference point in projection coordinates.
`Grid.y0`	Y reference point in projection coordinates.
`Grid.origin`	`'upper-left'` or `'lower-left'`.
`Grid.pixel_ref`	if coordinates are at the `'center'` or `'corner'` of the grid.
`Grid.x_coord`	x coordinates of the grid points (1D, no mesh)
`Grid.y_coord`	y coordinates of the grid points (1D, no mesh)
`Grid.xy_coordinates`	Tuple of x, y coordinates of the grid points.
`Grid.ll_coordinates`	Tuple of longitudes, latitudes of the grid points.
`Grid.xstagg_xy_coordinates`	Tuple of x, y coordinates of the X staggered grid.
`Grid.ystagg_xy_coordinates`	Tuple of x, y coordinates of the Y staggered grid.
`Grid.xstagg_ll_coordinates`	Tuple of longitudes, latitudes of the X staggered grid.
`Grid.ystagg_ll_coordinates`	Tuple of longitudes, latitudes of the Y staggered grid.
`Grid.center_grid`	`salem.Grid` instance representing the grid in center coordinates.
`Grid.corner_grid`	`salem.Grid` instance representing the grid in corner coordinates.
`Grid.extent`	[left, right, bottom, top] boundaries of the grid in the grid’s projection.

Grid methods¶

`Grid.extent_in_crs`	Get the extent of the grid in a desired crs.
`Grid.ij_to_crs`	Converts local i, j to cartesian coordinates in a specified crs
`Grid.almost_equal`	A less strict comparison between grids.
`Grid.region_of_interest`	Computes a region of interest (ROI).
`Grid.regrid`	Make a copy of the grid with an updated spatial resolution.
`Grid.transform`	Converts any coordinates into the local grid.
`Grid.map_gridded_data`	Reprojects any structured data onto the local grid.
`Grid.grid_lookup`	Performs forward transformation of any other grid into self.
`Grid.lookup_transform`	Performs the forward transformation of gridded data into self.
`Grid.to_dict`	Serialize this grid to a dictionary.
`Grid.from_dict`	Create a Grid from a dictionary
`Grid.to_json`	Serialize this grid to a json file.
`Grid.from_json`	Create a Grid from a json file
`Grid.to_dataset`	Creates an empty dataset based on the Grid’s geolocalisation.
`Grid.to_geometry`	Makes a geometrical representation of the grid (e.g.

Georeferencing utils¶

`check_crs`	Checks if the crs represents a valid grid, projection or ESPG string.
`proj_is_same`	Checks is two pyproj projections are equal.
`proj_to_cartopy`	Converts a pyproj.Proj to a cartopy.crs.Projection
`transform_proj`	Wrapper around the pyproj.transform function.
`transform_geometry`	Reprojects a shapely geometry.
`transform_geopandas`	Reprojects a geopandas dataframe.
`mercator_grid`	Local (transverse) mercator map centered on a specified point.
`grid_from_dataset`	Find out if the dataset contains enough info for Salem to understand.
`reduce`	Reduces an array’s size by a given factor.

Graphics¶

`DataLevels`	Assigns the right color to your data.
`Map`	Plotting georeferenced data.
`get_cmap`	Get a colormap from mpl, and also those defined by Salem.

Map & DataLevels methods¶

`DataLevels.append_colorbar`	Appends a colorbar to existing axes
`DataLevels.colorbarbase`	Returns a ColorbarBase to add to the cax axis.
`DataLevels.set_cmap`	Set a colormap.
`DataLevels.set_data`	Any kind of data array (also masked).
`DataLevels.set_plot_params`	Shortcut to all parameters related to the plot.
`DataLevels.set_extend`	Colorbar extensions: ‘neither’ \| ‘both’ \| ‘min’ \| ‘max’
`DataLevels.set_levels`	Levels you define.
`DataLevels.set_nlevels`	Automatic N levels.
`DataLevels.set_vmax`	Maximum level value.
`DataLevels.set_vmin`	Mininum level value.
`DataLevels.visualize`	Quick plot, useful for debugging.
`DataLevels.plot`	Add a kind of plot of the data to an axis.

Map methods¶

`Map.set_data`	Adds data to the plot.
`Map.set_contour`	Adds data to contour on the map.
`Map.set_contourf`	Adds data to contourfill on the map.
`Map.set_geometry`	Adds any Shapely geometry to the map.
`Map.set_lonlat_contours`	Add longitude and latitude contours to the map.
`Map.set_points`	Shortcut for set_geometry() accepting coordinates as input.
`Map.set_rgb`	Manually force to a rgb img
`Map.set_shapefile`	Add a shapefile to the plot.
`Map.set_text`	Add a text to the map.
`Map.set_topography`	Add topographical shading to the map.
`Map.set_scale_bar`	Add a legend bar showing the scale to the plot.
`Map.transform`	Get a matplotlib transform object for a given reference system
`Map.visualize`	Quick plot, useful for debugging.
`Map.plot`	Add the map plot to an axis.

Input/output¶

`get_demo_file`	Returns the path to the desired demo file.
`read_shapefile`	Reads a shapefile using geopandas.
`read_shapefile_to_grid`	Same as read_shapefile but directly transformed to a grid.

xarray¶

`open_xr_dataset`	Thin wrapper around xarray’s open_dataset.
`open_metum_dataset`	Wrapper to Met Office Unified Model files (experimental)
`open_wrf_dataset`	Wrapper around xarray’s open_dataset to make WRF files a bit better.
`open_mf_wrf_dataset`	Open multiple WRF files as a single WRF dataset.

xarray accessors¶

Salem adds accessors to xarray objects. They can be accessed via the .salem attribute and add the following methods:

DataArray¶

`DataArrayAccessor.subset`	Get a subset of the dataset.
`DataArrayAccessor.roi`	Make a region of interest (ROI) for the dataset.
`DataArrayAccessor.transform`	Reprojects an other Dataset or DataArray onto self.
`DataArrayAccessor.lookup_transform`	Reprojects an other Dataset or DataArray onto self using the forward tranform lookup.
`DataArrayAccessor.cartopy`	Get a cartopy.crs.Projection for this dataset.
`DataArrayAccessor.get_map`	Make a salem.Map out of the dataset.
`DataArrayAccessor.quick_map`	Make a plot of the DataArray.
`DataArrayAccessor.interpz`	Interpolates the array along the vertical dimension
`DataArrayAccessor.deacc`	De-accumulates the variable (i.e.

Dataset¶

`DatasetAccessor.subset`	Get a subset of the dataset.
`DatasetAccessor.roi`	Make a region of interest (ROI) for the dataset.
`DatasetAccessor.transform`	Reprojects an other Dataset or DataArray onto self.
`DatasetAccessor.lookup_transform`	Reprojects an other Dataset or DataArray onto self using the forward tranform lookup.
`DatasetAccessor.transform_and_add`	Reprojects an other Dataset and adds it’s content to the current one.
`DatasetAccessor.cartopy`	Get a cartopy.crs.Projection for this dataset.
`DatasetAccessor.get_map`	Make a salem.Map out of the dataset.
`DatasetAccessor.quick_map`	Make a plot of a variable of the DataSet.
`DatasetAccessor.wrf_zlevel`	Interpolates to a specified height above sea level.
`DatasetAccessor.wrf_plevel`	Interpolates to a specified pressure level (hPa).

Old-style datasets¶

Old-style Datasets (prior to xarray), kept for backwards compatibility reasons and because they are quite lightweight. They might be replaced by xarray’s datasets one day.

`GeoDataset`	Interface for georeferenced datasets.
`GeoTiff`	Geolocalised tiff images (needs rasterio).
`GeoNetcdf`	NetCDF files with geolocalisation info.
`WRF`	WRF proof-of-concept template.
`GoogleCenterMap`	Google static map centered on a point.
`GoogleVisibleMap`	Google static map automatically sized and zoomed to a selected region.

Other¶

geogrid_simulator Emulates geogrid.exe, which is useful when defining new WRF domains.