contourf issues with mpl3.8 #2224
Description
Description
I am sorry for raising this so late in the day, but I only today thought to test my "real work" against the upcoming releases. contourf seems occasionally very broken.
Code to reproduce
import cartopy.crs as ccrs
import matplotlib.pyplot as plt
import netCDF4
import numpy as np
fname = "z500_djf_bias.nc"
file2read = netCDF4.Dataset(fname,'r')
lons = file2read.variables['longitude'][:]
lats = file2read.variables['latitude'][:]
data = file2read.variables['unknown'][:]
fig, ax = plt.subplots(subplot_kw=dict(projection=ccrs.PlateCarree()))
levels = [-50, -40, -30, -20, -10, 10, 20, 30, 40, 50]
ax.contourf(lons, lats, data, levels=levels, cmap="RdBu_r", extend="both")
ax.coastlines()With Cartopy 0.21.1 and Matplotlib 3.7.2 I get
With Cartopy main and Matplotlib main I get
I have a variety of these plots and only some are affected, so I guess it's a function of exactly where the contours end up. Hence I attach a NetCDF file rather than attempting to create an example with dummy data.
Plotting the data array directly with Matplotlib looks sensible, and manually wrapping my data so the longitudes match the projection also gives me a sensible plot.
east = lons <= 180.
wrapped_lons = np.concatenate((lons[~east] - 360, lons[east]))
wrapped_data = np.concatenate((data[:, ~east], data[:, east]), axis=1)
fig, ax = plt.subplots(subplot_kw=dict(projection=ccrs.PlateCarree()))
ax.contourf(wrapped_lons, lats, wrapped_data, levels=levels, cmap="RdBu_r", extend="both")
ax.coastlines()So I think this might be specific to Cartopy's transforms, though I've no idea whether the fix should be here or in Matplotlib.
Full environment definition
Operating system
RHEL7
Cartopy version
main
conda list
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