Comment tracer un rectangle sur une carte cartopy avec python ?

Examples of how to plot a rectangle on a cartopy map with python:

Exemple 1 (PlateCarree projection)

from matplotlib.pyplot import figure

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
import cartopy.crs as ccrs

fig = figure(num=None, figsize=(12, 10), dpi=100, edgecolor='k')

proj = ccrs.PlateCarree()

ax = plt.axes(projection=proj)

ax.set_global()

long = -70.
lat = -45.

ax.add_patch(mpatches.Rectangle(xy=[long, lat], width=90, height=90,
                                facecolor='blue',
                                alpha=0.2,
                                transform=ccrs.PlateCarree())
             )

plt.scatter( long, lat,
             color='red', linewidth=2, marker='o', s=20,
             transform=ccrs.PlateCarree())

ax.gridlines()
ax.coastlines()

plt.title('How to plot a transparent rectangle on a map with cartopy ?')

plt.savefig("plot_rectangle_cartopy_01.png", bbox_inches='tight', facecolor='white')

plt.show()

Exemple 2 (Robinson projection)

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches

import cartopy.crs as ccrs

fig = figure(num=None, figsize=(12, 10), dpi=100, edgecolor='k')

proj = ccrs.Robinson()

ax = plt.axes(projection=proj)

ax.set_global()

ax.add_patch(mpatches.Rectangle(xy=[-70, -45], width=90, height=90,
                                facecolor='blue',
                                alpha=0.2,
                                transform=ccrs.PlateCarree())
             )

plt.scatter( -70, -45,
             color='red', linewidth=2, marker='o', s=20,
             transform=ccrs.PlateCarree())

ax.gridlines()
ax.coastlines()

plt.title('How to plot a transparent rectangle on a map with cartopy ?')

plt.savefig("plot_rectangle_cartopy_02.png", bbox_inches='tight', facecolor='white')

plt.show()

Exemple 3 using mpatches.Polygon

from matplotlib.pyplot import figure

import numpy as np
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import matplotlib.patches as mpatches

fig = figure(num=None, figsize=(12, 10), dpi=100, edgecolor='k')

map_proj = ccrs.PlateCarree()

ax = plt.axes(projection=map_proj)

ax.set_global()
ax.gridlines()

ax.coastlines(linewidth=0.5, color='k', resolution='50m')

lat_corners = np.array([-45.,  -45., -45.+90, -45.+90])
lon_corners = np.array([ -70., -70+90., -70.+90, -70.])

poly_corners = np.zeros((len(lat_corners), 2), np.float64)
poly_corners[:,0] = lon_corners
poly_corners[:,1] = lat_corners

poly = mpatches.Polygon(poly_corners, closed=True, ec='r', fill=True, lw=1, fc=None, transform=ccrs.PlateCarree())
ax.add_patch(poly)

plt.title('How to plot a transparent rectangle on a map with cartopy ?')

plt.savefig("plot_rectangle_cartopy_03.png", bbox_inches='tight', facecolor='white')

plt.show()

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