strorm track with customised legend on cartopy map

ex_cartopy_storm_track.py

#!/usr/bin/env python
"""
Demo: Plot strom tracks with custom legend on Cartopy mapping system
"""
import numpy as np
import cartopy.crs as ccrs
import cartopy.feature as cfeature
from cartopy.mpl import gridliner
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from collections import OrderedDict

# Create some dummy tracks (plane coordinates) and their properties

events = OrderedDict(    
    TD=np.array([[80,80,80,80],[5, 7, 9, 11]], dtype=np.float),
    TC=np.array([[80,79,80,81, 88],[11, 11, 11, 15, 15]], dtype=np.float)
)
labels = ['TD', 'TC']
colors = ['b', 'r']
extent = [50,120, -10, 30]  # x0, x1, y0, y1
legend_kw = dict(loc=9, bbox_to_anchor=(0.5, -0.1), ncol=2, frameon=False)

'''
dummy tracks and map extent defined here are on a cartesian plane;
update the projection parameters for actual data source.
See Cartopy supported projection list at
https://scitools.org.uk/cartopy/docs/latest/crs/projections.html
'''
data_proj = ccrs.PlateCarree()

# Example 1: Regular Data on Rectangular (PlateCarre) projection

plot_proj = ccrs.PlateCarree()

ax = plt.axes(projection=plot_proj)
ax.set_extent(extent, data_proj)
ax.coastlines()
gl = ax.gridlines(draw_labels=True)
gl.xformatter = gridliner.LONGITUDE_FORMATTER
gl.yformatter = gridliner.LATITUDE_FORMATTER
gl.xlabels_top, gl.ylabels_right = False, False
ax.add_feature(cfeature.BORDERS, lw=0.4, edgecolor='k')

patch = []
for i, item in enumerate(events):
    ax.plot(events[item][0], events[item][1], c=colors[i], transform=data_proj)
    patch.append(mpatches.Patch(color=colors[i], label=labels[i]))
    
_ = ax.legend(handles=patch, **legend_kw)

# Example 2: Regular Data on Robinson projection
# Limitation: Cartopy doesnot offer grid labeling in the projection

plot_proj = ccrs.Robinson()

ax = plt.axes(projection=plot_proj)
ax.set_extent(extent, data_proj)
ax.coastlines()
gl = ax.gridlines() 
ax.add_feature(cfeature.BORDERS, lw=0.4, edgecolor='k')

patch = []
for i, item in enumerate(events):
    ax.plot(events[item][0], events[item][1], c=colors[i], transform=data_proj)
    patch.append(mpatches.Patch(color=colors[i], label=labels[i]))
    
_ = ax.legend(handles=patch, **legend_kw)