python - Strange behavior with contours in Cartopy polar stereographic plot -

i'm trying create contour plot on north polar stereographic map projection using cartopy. used add_cyclic_point() try , around problem of having gap between longitude 0 , longitude 35x , followed example documentation (always_circular_stereographic) set map axes.

when call plt.contour, following plot. looks contour plotter getting confused @ transition 355 0 longitude, , sends contour lines around globe.

here code:

import numpy np import cartopy.crs ccrs cartopy.util import add_cyclic_point import matplotlib.pyplot plt  def define_map():     matplotlib.path import path      fig = plt.figure(figsize=(10,10))     ax = plt.axes(projection=ccrs.northpolarstereo())     ax.coastlines()      # example: http://scitools.org.uk/cartopy/docs/latest/examples/always_circular_stereo.html     theta = np.linspace(0, 2*np.pi, 100)     center, radius = [0.5, 0.5], 0.5     verts = np.vstack([np.sin(theta), np.cos(theta)]).t     circle = path(verts * radius + center)      ax.set_boundary(circle, transform=ax.transaxes)     return(fig, ax) lats = np.arange(65,91,5) lons = add_cyclic_point(np.arange(0,359,5)) data = add_cyclic_point(np.random.random((len(lats),len(lons)-1)))   fig, ax = define_map() plt.contour(lons,lats,data,5,transform=ccrs.platecarree(), cmap=plt.cm.blues) plt.colorbar(fraction=0.05, shrink=0.9) plt.show() 

how do cartopy contour plot properly? also, why contours show transform=ccrs.platecarree() , not transform=ccrs.northpolarstereo()?

apparently add_cyclic_point function data; contour routine treats 0 different 360. simple fix set

lons = np.arange(0,360,5)