Missing examples for the map and map_dataarray methods of FacetGrid objects

Abierto

#231 abierto el 23/12/2023 0 comentarios 1 reacción 0 asignados Ver en GitHub

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Evaluación

Dificultad: 3/5
Tiempo estimado: 1-2 días
Aptitud para principiantes: 45/100

Tipo de issue: Documentación
Claridad: Bastante claro
Estado de actividad: Estancado
Stack tecnológico: jupyter-notebook, matplotlib, numpy, pandas, python
Área: data-visualization, documentation

Línea de trabajo

The issue names no target file; start by locating the official FacetGrid documentation and existing examples for map and map_dataarray. Adapt the proposed air-temperature example to show both methods, and consider how the boolean overlay is represented. Done means newcomers can follow documented examples for adding hatching or stippling to faceted plots.

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Descripción

enhancement visualization

Faceted plots are a great feature of xarray, in my view, sometimes presented as a 'quick and dirty' way to plot data, while it could be instead the best way to produce high quality subplot panels without any tedious loop on matplotlib axes.
I have been struggling to understand how map and map_dataarray methods work to overlay, e.g. hatching or stippling to 2D faceted plots derived from xr.plot.pcolormesh or xr.plot.imshow . This is very useful to highlight values labelled as True after passing a statistical test for example.
I found a way to go with the map_dataarray method (Note that I have never succeeded in using the map method for datasets. I do not understand how it works).
Below, I propose an example based on the official documentation. Feel free to use it or adapt it to improve the Xarray documentation:

import numpy as np;
import pandas as pd;
import matplotlib.pyplot as plt;
import xarray as xr

airtemps = xr.tutorial.open_dataset("air_temperature")
air = airtemps.air - 273.15
t = air.isel(time=slice(0, 365 * 4, 250))
warm = t>15    #Suppose we want to hatch regions with temperature warmer than 15°C. Quite a dumb idea but this is just to illustrate
test = xr.concat([t,warm],dim='dummy')
g_simple = test.isel(dummy=0).plot(x="lon", y="lat", col="time", col_wrap=3)
g_simple.data = test.isel(dummy=1) #Here I just replace the temperature data of the FacetGrid object with the boolean data 
g_simple.map_dataarray(xr.plot.contourf,x='lon',y='lat', levels=3, hatches=[ '' , '////' ], alpha=0, add_colorbar=False)

plt.show()

Figure_1