Matplotlib-在极坐标图中绘制平滑圆 [英] Matplotlib - Drawing a smooth circle in a polar plot

问题描述

我真的很喜欢matplotlib的极坐标图，并希望继续使用它(因为无论如何我的数据点都是在极坐标中给出的，而且我的环境是圆形的).

I really like the polar plot of matplotlib and would love to keep working with it (since my data points are given in polar coordinates anyway and my environment is circular).

但是，在图中，我想在特定点添加给定半径的圆.

However, in the plot, I would like to add circles of given radii at specific points.

通常，我会这样做:

 ax = plt.subplot(111)
 ax.scatter(data)
 circle = plt.Circle((0,0), 0.5)
 ax.add_artist(circle)
 plt.show()

但是，在极坐标中，我不能使用圆，因为它假定是直角坐标.

However, in polar coordinates, I cannot use circle, since it assumes rectangular coordinates.

我想出的想法是:在[0，2PI]中生成具有恒定径向坐标和角坐标的点的数组，或完全切换为直角坐标.两种解决方案都不尽如人意-使用matplotlib可以做得更好吗?

Ideas I have come up with are: generating an array of points with constant radial coordinate and an angular coordinate in [0, 2PI] or completely switching to rectangular coordinates. Both solutions are not really satisfactory - can one do any better with matplotlib?

谢谢！

推荐答案

您可以设置Circle的transform自变量:

%matplotlib inline
import pylab as pl
import numpy as np

N = 100
theta = np.random.rand(N)*np.pi*2
r = np.cos(theta*2) + np.random.randn(N)*0.1

ax = pl.subplot(111, polar=True)
ax.scatter(theta, r)
circle = pl.Circle((0.5, 0.3), 0.2, transform=ax.transData._b, color="red", alpha=0.4)
ax.add_artist(circle)

输出:

或transform=ax.transProjectionAffine + ax.transAxes(如果您不喜欢使用private属性).

or transform=ax.transProjectionAffine + ax.transAxes if you don't like using the private attribute.

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