matplotlib - matplotlib：imshow 一个带有边缘密度图的二维数组

Question

如何 在 matplotlib中沿着 scatterplot-with-marginal-histograms-in-ggplot2 或 2D plot with histograms / margins 的线绘制 2d 密度及其边缘密度？概括地说，

    # I have --
A = a 2d numpy array >= 0
xdens ~ A.mean(axis=0)
ydens ~ A.mean(axis=1)

    # I want --
pl.imshow( A )
pl.plot( xdens ) narrow, below A
pl.plot( ydens ) narrow, left of A, with the x y axes flipped

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2017 年添加：参见seaborn.jointplot的可爱示例，也在SO 上。（问题是在 2013 年，在 seaborn 之前。）

Answer 1

您可以使用sharex和sharey与子图：

import numpy as np
import matplotlib.pyplot as plt
from matplotlib import gridspec

t = np.linspace(0, 31.3, 100)
f = np.linspace(0, 1000, 1000)
a = np.exp(-np.abs(f-200)/200)[:, None] * np.random.rand(t.size)
flim = (f.min(), f.max())
tlim = (t.min(), t.max())

gs = gridspec.GridSpec(2, 2, width_ratios=[1,3], height_ratios=[3,1])
ax = plt.subplot(gs[0,1])
axl = plt.subplot(gs[0,0], sharey=ax)
axb = plt.subplot(gs[1,1], sharex=ax)

ax.imshow(a, origin='lower', extent=tlim+flim, aspect='auto')
plt.xlim(tlim)

axl.plot(a.mean(1), f)
axb.plot(t, a.mean(0))

这给了你：