绘制给定点集的轮廓

Question

我有一组给定的点集 (x,y, F(x,y))，我想绘制一个等高线图，其中 (x,y) 显示为点，等高线计算为水平F(x,y) 的曲线。有谁知道如何用 seaborn 做到这一点？

我想要看起来像 sepal_width vs. sepal_length 的图作为 http://goo.gl/SWThWS（没有边缘），除了核密度估计应该不使用点的空间密度，而是 F(x,y)。

Answer 1

您可以将数据插值到二维网格中。有lots of ways to do this - probably the closest analogy to kernel density estimation would be to interpolate using a radial basis function:

import numpy as np
from scipy.interpolate import Rbf
from matplotlib import pyplot as plt

def f(x, y):
    return np.sin(x) + np.cos(2 * y)

# 1D arrays of points
x = np.random.rand(100) * 2 * np.pi
y = np.random.rand(100) * 2 * np.pi
z = f(x, y)

# initialize radial basis function
rb = Rbf(x, y, z)

# interpolate onto a 100x100 regular grid
X, Y = np.mgrid[:2*np.pi:100j, :2*np.pi:100j]
Z = rb(X.ravel(), Y.ravel()).reshape(X.shape)

# plotting
fig, ax = plt.subplots(1, 1)
ax.set_aspect('equal')
ax.hold(True)
m = ax.contourf(X, Y, Z, 20, cmap=plt.cm.Greens)
ax.scatter(x, y, c=z, s=60, cmap=m.cmap, vmin=m.vmin, vmax=m.vmax)
cb = fig.colorbar(m)
cb.set_label('$f(x, y)$', fontsize='xx-large')
ax.set_xlabel('$x$', fontsize='xx-large')
ax.set_ylabel('$y$', fontsize='xx-large')
ax.margins(0.05)
fig.tight_layout()
plt.show()

绘制给定点集的轮廓

Plot contours of a given set of points

python

plot

matplotlib

seaborn

contourf