如何使用 Matplotlib PolyCollection 绘制正方形？

Question

我试图通过尝试一个非常小的例子来理解PolyCollection中的 PolyCollection 到 plot 一个正方形（我知道已经有补丁/艺术家）但我想了解我应该如何指定PolyCollection的顶点。

我尝试了以下方法：

import matplotlib.pyplot as plt
from matplotlib.collections import PolyCollection
import numpy as np

verts = [[0.0,0.0],[1.0,0.0],[1.0,1.0],[0.0,1.0]]
verts = np.array(verts)
print(verts.shape)

poly = PolyCollection(verts, facecolors = 'blue', edgecolors='k', linewidth=1)

fig = plt.figure()
ax = fig.add_subplot(111)
ax.set_xlim(-1.5, 1.5)
ax.set_ylim(-1.5, 1.5)

ax.add_collection(poly)

plt.show()

但我收到以下错误：

main.py 9 <module>
poly = PolyCollection(verts, facecolors = 'blue', edgecolors='k', linewidth=1)

collections.py 1189 __init__
self.set_verts(verts, closed)

collections.py 1234 set_verts
self._paths.append(mpath.Path(xy, closed=True))

path.py 130 __init__
_api.check_shape((None, 2), vertices=vertices)

__init__.py 164 check_shape
raise ValueError(

ValueError:
'vertices' must be 2D with shape (M, 2). Your input has shape (3,).

我的顶点已经有了形状(4,2) 。

我做错了什么？

Answer 1

verts应该是二维数组序列的列表。

PolyCollection?

Init signature: PolyCollection(verts, sizes=None, closed=True, **kwargs)
Docstring:      Base class for collections that have an array of sizes.
Init docstring:
Parameters
----------
verts : list of array-like
    The sequence of polygons [*verts0*, *verts1*, ...] where each
    element *verts_i* defines the vertices of polygon *i* as a 2D
    array-like of shape (M, 2).

由于您只绘制一个正方形，因此您可以这样写：

square_verts = [[0.0,0.0],[1.0,0.0],[1.0,1.0],[0.0,1.0]]
poly = PolyCollection([square_verts], facecolors = 'blue', edgecolors='k', linewidth=1)