python - 如何轻松地将颜色图应用于线图？

Question

我找到了这个例子multicolored lines生成这些图:

那里的代码使用了 reshaped 连接的 x,y 值的 LineCollection，这看起来相当麻烦。是否没有更简单的方法将颜色图应用于线图？像 plot(x, y, cmap='viridis', Colors=dxdy) 之类的东西？为了澄清起见，我不是在询问使用颜色图来设置多条线的恒定颜色(如所述，例如 here )，而是在询问将颜色图应用到非恒定颜色的单线上。

<小时/>

为了完整起见，以下是该示例的代码:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection
from matplotlib.colors import ListedColormap, BoundaryNorm

x = np.linspace(0, 3 * np.pi, 500)
y = np.sin(x)
dydx = np.cos(0.5 * (x[:-1] + x[1:]))  # first derivative

# Create a set of line segments so that we can color them individually
# This creates the points as a N x 1 x 2 array so that we can stack points
# together easily to get the segments. The segments array for line collection
# needs to be (numlines) x (points per line) x 2 (for x and y)
points = np.array([x, y]).T.reshape(-1, 1, 2)
segments = np.concatenate([points[:-1], points[1:]], axis=1)

fig, axs = plt.subplots(2, 1, sharex=True, sharey=True)

# Create a continuous norm to map from data points to colors
norm = plt.Normalize(dydx.min(), dydx.max())
lc = LineCollection(segments, cmap='viridis', norm=norm)
# Set the values used for colormapping
lc.set_array(dydx)
lc.set_linewidth(2)
line = axs[0].add_collection(lc)
fig.colorbar(line, ax=axs[0])

# Use a boundary norm instead
cmap = ListedColormap(['r', 'g', 'b'])
norm = BoundaryNorm([-1, -0.5, 0.5, 1], cmap.N)
lc = LineCollection(segments, cmap=cmap, norm=norm)
lc.set_array(dydx)
lc.set_linewidth(2)
line = axs[1].add_collection(lc)
fig.colorbar(line, ax=axs[1])

axs[0].set_xlim(x.min(), x.max())
axs[0].set_ylim(-1.1, 1.1)
plt.show()

Answer 1

不，没有“更简单”的方法。这就是我们在文档中提供该示例的原因。