在 matplotlib 的底图中设置经度和纬度线的线型？

Question

我正在使用 maplotlib 的 Basemap 绘制世界地图并希望包括经度和纬度线。这可以使用 drawmeridians() 和 drawparallels() 来完成，但是相应线条的线型只能通过关键字 dashes 来设置。根据文档，请参阅 see here，应该按如下方式工作：

dash pattern for meridians (default [1,1], i.e. 1 pixel on, 1 pixel off)

我尝试了 dashes=[1,0] 但没有成功。有没有什么简单的方法可以让线条更立体？

这是我的代码：

import matplotlib.pyplot as plt
import numpy as np
from mpl_toolkits.basemap import Basemap

fig1, ax1 = plt.subplots(1,1)

map1 = Basemap( resolution='l', projection='mill',
                llcrnrlat=-60., llcrnrlon=-180.,
                urcrnrlat=90.,  urcrnrlon=180. )

map1.drawcoastlines()
map1.drawmapboundary( fill_color='aqua' )
map1.fillcontinents( color='coral', lake_color='aqua' )

# labels=[left,right,top,bottom]
map1.drawparallels( np.arange(-80.,81.,20.),   labels=[True,True,False,False] )
map1.drawmeridians( np.arange(-180.,181.,40.), labels=[False,False,True,True] )

plt.show()

这是生成的地图：

编辑 1：我刚在另一台计算机上试过，它可以工作，即 dashes=[1,0] 产生实线样式。该计算机上使用的版本是（根据 pip freeze）

basemap==1.2.0

matplotlib==2.2.3

一旦我再次访问原来的计算机，我将检查那里发生了什么（以及安装了哪些版本）。

编辑 2：回到它无法工作的计算机前，我现在可以说得更多了。首先，使用以下版本：

basemap==1.1.1

matplotlib==3.0.2

然后是错误信息（我之前忘了包括）：

ValueError: All values in the dash list must be positive

编辑 3：为了完整起见（并且因为它对寻找解决方案有一定帮助），这里是完整的 Traceback:

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1540, in __call__
    return self.func(*args)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/backends/backend_tkagg.py", line 280, in resize
    self.show()
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/backends/backend_tkagg.py", line 351, in draw
    FigureCanvasAgg.draw(self)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/backends/backend_agg.py", line 464, in draw
    self.figure.draw(self.renderer)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/figure.py", line 1143, in draw
    renderer, self, dsu, self.suppressComposite)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/image.py", line 139, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 2409, in draw
    mimage._draw_list_compositing_images(renderer, self, dsu)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/image.py", line 139, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/lines.py", line 822, in draw
    drawFunc(renderer, gc, tpath, affine.frozen())
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/lines.py", line 1267, in _draw_lines
    self._lineFunc(renderer, gc, path, trans)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/lines.py", line 1297, in _draw_dashed
    gc.set_dashes(self._dashOffset, self._dashSeq)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/backend_bases.py", line 1007, in set_dashes
    raise ValueError("All values in the dash list must be positive")

Answer 1

在研究 github 上的一些错误报告后，我找到了解决方案 [1]，dashes=(None,None)：

map1.drawmeridians( np.arange(-180.,181.,40.), labels=[False,False,True,True], dashes=(None,None) )

[1] https://github.com/matplotlib/basemap/issues/173#issuecomment-68243710

在 matplotlib 的底图中设置经度和纬度线的线型？

Setting the linestyle for the longitude and latitude lines in matplotlib's Basemap?

python

matplotlib

matplotlib-basemap