NCL_maponly_1.py

This script illustrates the following concepts:

• Drawing a cylindrical equidistant map using Cartopy

• Adding Cartopy land feature to map

• Adding longitude and latitude tick marks

• Adding major and minor tick marks

See following URLs to see the reproduces NCL plot & script:

• Original NCL script: https://www.ncl.ucar.edu/Applications/Scripts/maponly_1.ncl

• Original NCL plot: https://www.ncl.ucar.edu/Applications/Images/maponly_1_lg.png

Import packages:

import cartopy.crs as ccrs
import cartopy.feature as cfeature
import matplotlib.pyplot as plt
import numpy as np

import geocat.viz.util as gvutil

Plot:

# Generate axes using Cartopy
ax = plt.axes(projection=ccrs.PlateCarree())

# Draw land
ax.add_feature(cfeature.LAND, color='silver')

# Use geocat.viz.util convenience function to set axes tick values
gvutil.set_axes_limits_and_ticks(ax,
                                 xticks=np.linspace(-180, 180, 13),
                                 yticks=np.linspace(-90, 90, 7))

# Use geocat.viz.util convenience function to make lat/lon tick labels
gvutil.add_lat_lon_ticklabels(ax)

# Use geocat.viz.util convenience function to add major and minor tick marks
gvutil.add_major_minor_ticks(ax)

# Show plot
plt.show()