norm argument is not passed correctly to uds.ugrid.plot() #49
Description
I noticed that the norm argument is not passed correctly to the Polycollection. This quite large MWE should provide two identical plots, one with a manual setup Polycollection and one with the uds.ugrid.plot() method. When passing norm!=None, the colorbar is incorrect. When passing norm=None, the plots are identical.
EDIT: this also happens when plotting normal xarray instances, so it is probably not xugrid related. Also, I found that plotting with pcolormesh does work, so it might be something xarray internal.
import os
import matplotlib.pyplot as plt
plt.close('all')
import dfm_tools as dfmt
import matplotlib as mpl
import numpy as np
file_nc = os.path.join(r'c:\DATA\dfm_tools_testdata','DFM_3D_z_Grevelingen','computations','run01','DFM_OUTPUT_Grevelingen-FM','Grevelingen-FM_0*_map.nc')
cmap = mpl.cm.get_cmap("viridis")
clim_bl = [-35,10]
start,stop = clim_bl
step = 4
boundaries = np.array([i for i in np.arange(start, stop, step)])
norm = mpl.colors.BoundaryNorm(boundaries, cmap.N) #setting this to None results in equal plots, when not None the ugrid plot is wrong
data_frommap_merged = dfmt.open_partitioned_dataset(file_nc)
ugrid_all_verts = dfmt.get_ugrid_verts(data_frommap_merged)
data_frommap_raster = dfmt.rasterize_ugrid(data_frommap_merged, resolution=400)
#get bedlevel and create plot with ugrid and cross section line
fig, (ax1,ax2,ax3,ax4) = plt.subplots(4,1,figsize=(5,9))
pc1 = mpl.collections.PolyCollection(ugrid_all_verts, linewidth=0.5, edgecolors='face', cmap=cmap, norm=norm)
pc1.set_array(data_frommap_merged['mesh2d_flowelem_bl'].to_numpy())
ax1.add_collection(pc1)
ax1.autoscale() #necessary to call manually
fig.colorbar(pc1,ax=ax1, extend = 'max')
pc1.set_clim(clim_bl)
ax1.set_aspect('equal')
ax1.set_title('matplotlib.PolyCollection(verts)')
pc2 = data_frommap_merged['mesh2d_flowelem_bl'].ugrid.plot(linewidth=0.5, edgecolor='face',cmap=cmap, ax=ax2, norm=norm, add_colorbar=False)
fig.colorbar(pc2,ax=ax2, extend = 'max')
pc2.set_clim(clim_bl)
ax2.set_aspect('equal')
ax2.set_title('uda.ugrid.plot()')
pc3 = data_frommap_raster['mesh2d_flowelem_bl'].plot(linewidth=0.5, edgecolor='face', cmap=cmap, ax=ax3, norm=norm, add_colorbar=False)
fig.colorbar(pc3,ax=ax3, extend = 'max')
pc3.set_clim(clim_bl)
ax3.set_aspect('equal')
ax3.set_title('da.plot() (rasterized uds)')
pc4 = ax4.pcolormesh(data_frommap_raster.x,data_frommap_raster.y,data_frommap_raster['mesh2d_flowelem_bl'].values, cmap=cmap, norm=norm)
fig.colorbar(pc4,ax=ax4, extend = 'max')
pc4.set_clim(clim_bl)
ax4.set_aspect('equal')
ax4.set_title('ax.pcolormesh(x,y,da) (rasterized uds)')
fig.tight_layout()
