IndexError - 笛卡尔 PolygonPatch 与 shapely

Question

我曾经使用 shapely 制作一个圆圈并将其绘制在之前填充的图上。这曾经工作得很好。最近，我收到索引错误。我将代码分解为最简单的操作，但它甚至无法执行最简单的循环。

import descartes
import shapely.geometry as sg
import matplotlib.pyplot as plt

circle = sg.Point((0,0)).buffer(1)

# Plot the cricle
fig = plt.figure()
ax = fig.add_subplot(111)
patch = descartes.PolygonPatch(circle)
ax.add_patch(patch)
plt.show()

以下是我现在遇到的错误。我觉得这可能是新版本与可能发生的事情不匹配。我尝试卸载并重新安装最后一个已知的稳定版本，但这也没有帮助

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
Cell In[20], line 6
      4 fig = plt.figure()
      5 ax = fig.add_subplot(111)
----> 6 patch = descartes.PolygonPatch(circle)
      7 ax.add_patch(patch)
      8 plt.show()

File ~/env/lib/python3.8/site-packages/descartes/patch.py:87, in PolygonPatch(polygon, **kwargs)
     73 def PolygonPatch(polygon, **kwargs):
     74     """Constructs a matplotlib patch from a geometric object
     75 
     76     The `polygon` may be a Shapely or GeoJSON-like object with or without holes.
   (...)
     85 
     86     """
---> 87     return PathPatch(PolygonPath(polygon), **kwargs)

File ~/env/lib/python3.8/site-packages/descartes/patch.py:62, in PolygonPath(polygon)
     58     else:
     59         raise ValueError(
     60             "A polygon or multi-polygon representation is required")
---> 62 vertices = concatenate([
     63     concatenate([asarray(t.exterior)[:, :2]] +
     64                 [asarray(r)[:, :2] for r in t.interiors])
     65     for t in polygon])
     66 codes = concatenate([
     67     concatenate([coding(t.exterior)] +
     68                 [coding(r) for r in t.interiors]) for t in polygon])
     70 return Path(vertices, codes)

File ~/env/lib/python3.8/site-packages/descartes/patch.py:63, in <listcomp>(.0)
     58     else:
     59         raise ValueError(
     60             "A polygon or multi-polygon representation is required")
     62 vertices = concatenate([
---> 63     concatenate([asarray(t.exterior)[:, :2]] +
     64                 [asarray(r)[:, :2] for r in t.interiors])
     65     for t in polygon])
     66 codes = concatenate([
     67     concatenate([coding(t.exterior)] +
     68                 [coding(r) for r in t.interiors]) for t in polygon])
     70 return Path(vertices, codes)

IndexError: too many indices for array: array is 0-dimensional, but 2 were indexed

Answer 1

因此，据我所知，这个问题来自shapelyinside的错误实现descartes。

我的猜测是，它shapely改变了它处理多边形外部的方式，并且descartes根本没有更新。

我不知道这是否是最好的主意，但我descartes直接编辑了我的安装来解决这个问题：

1. 导航到您的descartes安装并打开patch.py.

2. 在第 62 行，您应该看到这段代码：

    vertices = concatenate([
    concatenate([asarray(t.exterior)[:, :2]] + [asarray(r)[:, :2] for r in t.interiors])
    for t in polygon])
   

只需更改t.exterior为t.exterior.coords. 这有望解决您的问题。

    vertices = concatenate([
    concatenate([asarray(t.exterior.coords)[:, :2]] + [asarray(r)[:, :2] for r in t.interiors])
    for t in polygon])

我正在尝试找到一种方法向descartes开发人员提供此反馈。