matplotlib - 沿绘图线改变标记颜色

Question

我想用matplotlib绘制一个2d数据集,使每个数据点的标记颜色不同.我在五彩线上找到了这个例子(http://matplotlib.org/examples/pylab_examples/multicolored_line.html).但是,在绘制带标记的线条时,这似乎不起作用.

我想出的解决方案是单独绘制每一点:

import matplotlib.cm as cm
import matplotlib.pyplot as plt
import numpy as np

# The data
x = np.linspace(0, 10, 1000)
y = np.sin(2 * np.pi * x)

# The colormap
cmap = cm.jet

# Create figure and axes
fig = plt.figure(1)
fig.clf()
ax = fig.add_subplot(1, 1, 1)

# Plot every single point with different color
for i in range(len(x)):
    c = cmap(int(np.rint(x[i] / x.max() * 255)))
    ax.plot(x[i], y[i], 'o', mfc=c, mec=c)
    ax.set_xlim([x[0], x[-1]])
    ax.set_ylim([-1.1, 1.1])
    ax.set_xlabel('x')
    ax.set_ylabel('y')

plt.draw()
plt.show()

# Save the figure
fig.savefig('changing_marker_color.png', dpi=80)

结果情节看起来应该如此,但绘图变得非常慢,我需要它很快.加速绘图是否有一个聪明的伎俩？

Answer 1

我相信你可以通过以下方式达到ax.scatter:

# The data
x = np.linspace(0, 10, 1000)
y = np.sin(2 * np.pi * x)

# The colormap
cmap = cm.jet

# Create figure and axes
fig = plt.figure(1)
fig.clf()
ax = fig.add_subplot(1, 1, 1)

c = np.linspace(0, 10, 1000)
ax.scatter(x, y, c=c, cmap=cmap)

Scatter接受c作为浮点序列,它将使用cmap映射到颜色.

使用timeit时间减少10倍(原始方法约为1.25秒,此处为76.8毫秒)