Map plotting tools for gridded data

Created on 24 Mai 2025

Authors:

radanovics

largely copied from epygram epy_cartoplot.py

plots.maps.quicklookmap.difference_map(field, ref_field, title, plot_kwargs={})

Plot a difference map between two fields.

Parameters:

• field (epygram H2D field) – first scalar field

• ref_field (epygram H2D field) – reference field to substract.

• title (str) – plot title

• plot_kwargs – every other argument that can be passed to the cartoplot method of an epygram H2D field.

Returns:

dict with plot elements: ‘fig’, ‘ax’, potentially ‘colorbar’ etc.

Return type:

dict

plots.maps.quicklookmap.read_and_preprocess(resource, fid, date, operation=None, global_shift_center=None, zoom=None)

Read field in resource, and preprocess if requested.

Parameters:

• resource (epygram.resource) – epygram resource to read data from

• fid (epygram field idenifier depending on the resource type. for example str for NetCDF files or a dict for grib files) – field identifier

• date (bronx.Date) – date (with time)

• operation (dict) – makes the requested operation (e.g. {‘operation’:’-‘,’operand’:273.15} or {‘operation’:’exp’}) on the field before plot. default=None

• global_shift_center – for global lon/lat grids, shift the center by the requested angle (in degrees). Enables a [0,360] grid to be shifted to a [-180,180] grid, for instance (with -180 argument).

• zoom (dict) – a dict(lonmin, lonmax, latmin, latmax) on which to build the plot.

Returns:

field

Return type:

epygram.field

plots.maps.quicklookmap.scalar_map(field, title, plot_kwargs)

Plot a map.

Parameters:

• field (epygram H2DField or H2DVectorField) – field to plot

• title (str) – plot title

• plot_kwargs – every other argument that can be passed to the cartoplot method of an epygram H2D field.

Returns:

dict with plot elements: ‘fig’, ‘ax’, potentially ‘colorbar’ etc.

Return type:

dict

plots.maps.quicklookmap.wind_map(field, title, map_factor_correction=False, vectors_subsampling=50, wind_components_are_projected_on=None, vector_plot_method='quiver', quiverkey=None, plot_kwargs={})

Plot a map of a vector field.

Parameters:

• field (epygram vector field) – vector field to plot

• title (str) – plot title

• map_factor_correction (bool) – if True, applies a correction of magnitude to vector due to map factor.

• vectors_subsampling (int) – subsampling ratio of vectors plots. for example: 1 for a vector at every gridpoint, 10 for a vector every 10 grid points.

• wind_components_are_projected_on – inform the plot on which axes the vector components are projected on (‘grid’ or ‘lonlat’). If None (default), look for information in the field, or raise error.

• vector_plot_method – among (‘quiver’, ‘barbs’, ‘streamplot’) for vector plots. default is ‘quiver’.

• quiverkey – options to be passed to plotfield to activate a quiver key (cf. pyplot.quiverkey).

• plot_kwargs – every other argument that can be passed to the cartoplot method of an epygram H2D field.

Returns:

dict with plot elements: ‘fig’, ‘ax’, potentially ‘colorbar’ etc.

Return type:

dict