central_longitude=180 时无法在右侧显示 0 刻度

Question

当其他条件如+180 和-180 时，它会转正。当0应该在右边时，它没有出现。

没有正确的0，网站的结果是一样的

https://scitools.org.uk/cartopy/docs/latest/gallery/tick_labels.html?highlight=tick

我已经阅读了geoaxes的代码并尝试了另一种方法来在右边显示0。

如果使用matplotlib方法结果更错误。

如果使用 Cartopy 地图网格线和刻度标签，结果是一样的。

https://scitools.org.uk/cartopy/docs/latest/matplotlib/gridliner.html#cartopy.mpl.gridliner.Gridliner.xformatter

#===================================================
#plot the world map central 180 
#===================================================
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
from cartopy.mpl.ticker import LongitudeFormatter, LatitudeFormatter
def make_map(scale):
    fig=plt.figure(figsize=(8, 10))
    ax=plt.axes(projection=ccrs.PlateCarree(central_longitude=180))
    ax.set_global()
    land = cfeature.NaturalEarthFeature('physical', 'land', scale,edgecolor='face',
                                                              facecolor=cfeature.COLORS['land'])
    ax.add_feature(land, facecolor='0.75')
    ax.coastlines(scale)
    #===set tick
    ax.set_xticks([0, 60, 120, 180, 240, 300, 360], crs=ccrs.PlateCarree())
    ax.set_yticks([-90, -60, -30, 0, 30, 60, 90], crs=ccrs.PlateCarree())

    lon_formatter = LongitudeFormatter(zero_direction_label=False)
    lat_formatter = LatitudeFormatter()
    ax.xaxis.set_major_formatter(lon_formatter)
    ax.yaxis.set_major_formatter(lat_formatter)
    #=====set grid
    #gl = ax.gridlines()
    ax.grid()
    return fig,ax
fig,ax=make_map(scale='110m')

如何让 0 显示在轴的右侧？

Answer 1

对我来说，看起来应该出现在右边的零也出现在左边；请注意那个滴答标签是如何比其他标签更大胆的？！

原因似乎是 360 % 360 == 0，所以刻度围绕着开始。

一个解决方法是将最后一个刻度稍微移动一下，比如

[0, 60, 120, 180, 240, 300, 359.9999999999]

或

[0, 60, 120, 180, -120, -60, -1e-10]

示例：

import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
from cartopy.mpl.ticker import LongitudeFormatter, LatitudeFormatter
def make_map(scale):
    fig=plt.figure(figsize=(8, 6))
    ax=plt.axes(projection=ccrs.PlateCarree(central_longitude=180))
    ax.set_global()
    land = cfeature.NaturalEarthFeature('physical', 'land', scale,edgecolor='face',
                                        facecolor=cfeature.COLORS['land'])
    ax.add_feature(land, facecolor='0.75')
    ax.coastlines(scale)

    ax.set_xticks([0, 60, 120, 180, 240, 300, 359.9999999999], crs=ccrs.PlateCarree())
    ax.set_yticks([-90, -60, -30, 0, 30, 60, 90], crs=ccrs.PlateCarree())

    lon_formatter = LongitudeFormatter(zero_direction_label=True)
    lat_formatter = LatitudeFormatter()
    ax.xaxis.set_major_formatter(lon_formatter)
    ax.yaxis.set_major_formatter(lat_formatter)

    ax.grid()
    return fig,ax

fig,ax=make_map(scale='110m')
plt.show()

central_longitude=180 时无法在右侧显示 0 刻度

can't show 0 tick in right when central_longitude=180

matplotlib

python-3.x

cartopy