为什么pcolormesh和带有定制颜色条的contourf plot之间显示的颜色条不同

我已经改编了一个定制的颜色比例从 NCL 跟随离散间隔颜色条 example . 我的数据数组位于NetCDF文件中,当我尝试打印它时,打印和颜色栏看起来与预期的一样 pcolormesh 但当我策划时,它会变得疯狂 contourf 情节我是不是在做错事 决定性的 色阶?

import matplotlib.colors
import xarray as xr

# loading data

ds = xr.open_dataset(path/tofile/data.nc)


## custom color bar
## converting RGB values to 0,1
cmap3 =  matplotlib.colors.ListedColormap([(127/255, 150/255, 255/255), (142/255, 178/255, 255/255), (181/255, 201/255, 255/255), (214/255, 226/255, 237/255),\
(242/255, 221/255, 160/255), (242/255, 132/255, 68/255), (229/255, 0/255, 0/255), (1, 163/255, 10/255), (1, 249/255, 20/255), (172/255, 206/255, 100/255), (125/255, 190/255, 84/255)])

# I want to discretize the colorbar according to values
vals = [-1.0, 0.0, 0.2 ,0.5, 0.8, 1.0, 1.5, 2.0, 4.0 , 6.0 , 8.0,  10]
norm = matplotlib.colors.BoundaryNorm(vals, cmap3.N)

# variable to be plotted
ds.PV.squeeze().plot.pcolormesh(cmap=cmap3, norm=norm, vmin=0, vmax=10)
# contourf plot which is giving unexpected result
ds.PV.squeeze().plot.contourf(cmap=cmap3, norm=norm, vmin=0, vmax=10)

具有Pcolormesh绘图的预期颜色比例:

绘制轮廓图时颜色比例错误:

下面是具有默认颜色比例的轮廓图

这就是我的 对的

fig, ax =plt.subplots(figsize=(6,1))

cb3 = matplotlib.colorbar.ColorbarBase(ax, cmap=cmap3,
                            norm=norm,
                            extend='neither',
                            ticks=vals,
                            spacing='uniform',
                            orientation='horizontal')