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

ax = plt.axes(projection=ccrs.PlateCarree())
ax.coastlines()
plt.show()

ax = plt.axes(projection=ccrs.PlateCarree())
ax.coastlines()
ax.set_global()
plt.plot([-100, 50], [25, 25], linewidth=4, transform=ccrs.Geodetic())
plt.show()

ax = plt.axes(projection=ccrs.Mercator())
ax.coastlines()
gl = ax.gridlines(draw_labels=True)
plt.show()

import matplotlib.ticker as mticker
from cartopy.mpl.gridliner import LATITUDE_FORMATTER

ax = plt.axes(projection=ccrs.PlateCarree())
ax.coastlines()
gl = ax.gridlines(draw_labels=True)

gl.xlocator = mticker.FixedLocator([-180, -45, 0, 45, 180])
gl.yformatter = LATITUDE_FORMATTER

plt.show()

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

x = np.linspace(310, 390, 25)
y = np.linspace(-24, 25, 35)
x2d, y2d = np.meshgrid(x, y)

data = np.cos(np.deg2rad(y2d) * 4) + np.sin(np.deg2rad(x2d) * 4)