使用Axes.pie的inset_axes隐藏的Cartopy海岸线 [英] Cartopy coastlines hidden by inset_axes use of Axes.pie

问题描述

我正在用单独的模型网格框中的饼图制作世界地图.我使用Cartopy绘制地图和海岸线.我使用inset_axes生成的饼图.不幸的是，饼图隐藏了海岸线，我想清楚地看到它们.

I am producing a map of the world with pie charts in individual model grid boxes. I make the map and coastlines using cartopy. The pie charts I produce using inset_axes. Unfortunately the pie charts hide the coastlines and I'd like to see them clearly.

最小工作示例:

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

def plot_pie_inset(dataframe_pie,ilat_pie,ilon_pie,axis_main,width_local,alpha_local):
    ax_sub= inset_axes(axis_main, width=width_local, height=width_local, loc=3, bbox_to_anchor=(ilat_pie, ilon_pie),bbox_transform=axis_main.figure.transFigure, borderpad=0.0)
    wedges,texts= ax_sub.pie(dataframe_pie,colors=colors_dual)
    for w in wedges:
        w.set_linewidth(0.02)
        w.set_alpha(alpha_local)
        w.set_zorder(1)
    plt.axis('equal')

colors_dual=['RosyBrown','LightBlue']
lat_list= np.arange(0.2,0.7,0.05)

fig= plt.figure()
ax_main= plt.subplot(1,1,1,projection=ccrs.PlateCarree())
ax_main.coastlines(zorder=3)
for ilat in np.arange(len(lat_list)):
    plot_pie_inset([75,25],lat_list[ilat],0.72,ax_main,0.2,0.9)

plt.show()

我可以通过减小alpha值使饼图部分透明来看到海岸线.但是，这会使颜色有些柔和.我的目标是使海岸线成为最顶层.

I can see the coastlines by making the pie charts partially transparent by reducing the alpha value. However, this makes the colors somewhat muted. My aim is to have the coastlines as the topmost layer.

我尝试使用"zorder"将海岸线强制到顶层.但是，"zorder"不能传递给inset_axes，也不能传递给ax.pie，因此我使饼图中的色块变得半透明.之所以失败，是因为ax_main.coastlines没有自己的"zorder".海岸线zorder似乎与ax_main紧密相关.增加ax_main的zorder没有任何好处.

I have attempted to use 'zorder' to force the coastlines to the top layer. However, 'zorder' cannot be passed to inset_axes, nor to ax.pie so I've made the patches of color in pie charts translucent. This fails because the ax_main.coastlines does not have its own 'zorder'. The coastline zorder seems to be tied to that of ax_main. There is no benefit in increasing the zorder of ax_main.

任何建议都将受到欢迎.

Any suggestions greatly welcomed.

推荐答案

问题是每个轴位于另一个轴的上方或下方.因此，在轴内更改艺术家的zorder并没有帮助.原则上，可以设置轴本身的zorder，将插入轴放在主轴后面.

The problem is that each axes either lies on top or below another axes. So changing the zorder of artists within axes, does not help here. In principle, one could set the zorder of the axes themselves, putting the inset axes behind the main axes.

ax_sub.set_zorder(axis_main.get_zorder()-1)

Cartopy的GeoAxes使用其自己的背景补丁.然后需要将其设置为不可见.

Cartopy's GeoAxes uses its own background patch. This would then need to be set to invisble.

ax_main.background_patch.set_visible(False)

完整示例:

import cartopy.crs as ccrs
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1.inset_locator import inset_axes

def plot_pie_inset(dataframe_pie,ilat_pie,ilon_pie,axis_main,width_local,alpha_local):
    ax_sub= inset_axes(axis_main, width=width_local, height=width_local, loc=3, 
                       bbox_to_anchor=(ilat_pie, ilon_pie),
                       bbox_transform=axis_main.transAxes, 
                       borderpad=0.0)
    wedges,texts= ax_sub.pie(dataframe_pie,colors=colors_dual)
    for w in wedges:
        w.set_linewidth(0.02)
        w.set_alpha(alpha_local)
        w.set_zorder(1)
    plt.axis('equal')
    # Put insets behind main axes
    ax_sub.set_zorder(axis_main.get_zorder()-1)

colors_dual=['RosyBrown','LightBlue']
lat_list= np.arange(0.2,0.7,0.05)

fig= plt.figure()
ax_main= plt.subplot(1,1,1,projection=ccrs.PlateCarree())
ax_main.coastlines()

# set background patch invisible, such that axes becomes transparent
# since the GeoAxes from cartopy uses a different patch as background
# the following does not work
# ax_main.patch.set_visible(False)
# so we need to set the GeoAxes' background_patch invisible
ax_main.background_patch.set_visible(False)

for ilat in np.arange(len(lat_list)):
    plot_pie_inset([75,25],lat_list[ilat],0.72,ax_main,0.2,0.9)

plt.show()

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