python matplotlib,带有线条颜色渐变和颜色条

Question

我一直在努力解决这个问题,并且接近我想要的但却错过了额外的一两行.

基本上,我想绘制一条线,其颜色根据第三个数组的值而变化.潜伏在周围我发现这很好用(虽然很慢)并且代表了问题

import numpy as np
import matplotlib.pyplot as plt
c = np.arange(1,100)
x = np.arange(1,100)
y = np.arange(1,100)

cm = plt.get_cmap('hsv')

fig = plt.figure(figsize=(5,5))
ax1 = plt.subplot(111)

no_points = len(c)
ax1.set_color_cycle([cm(1.*i/(no_points-1)) 
                     for i in range(no_points-1)])

for i in range(no_points-1):
    bar = ax1.plot(x[i:i+2],y[i:i+2])
plt.show()

这给了我这个:

我希望能够在此图中包含一个颜色条.到目前为止,我还没有能够破解它.可能会有其他行包含不同的x,y但是相同的c,所以我认为Normalize对象将是正确的路径.

更大的图片是这个图是2x2子图网格的一部分.我已经使用matplotlib.colorbar.make_axes(ax4)为颜色条轴对象创建空间,其中ax4具有第4个子图.

Answer 1

看看在multicolored_line例如在Matplotlib画廊和dpsanders' colorline笔记本:

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.collections as mcoll

def multicolored_lines():
    """
    http://nbviewer.ipython.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb
    http://matplotlib.org/examples/pylab_examples/multicolored_line.html
    """

    x = np.linspace(0, 4. * np.pi, 100)
    y = np.sin(x)
    fig, ax = plt.subplots()
    lc = colorline(x, y, cmap='hsv')
    plt.colorbar(lc)
    plt.xlim(x.min(), x.max())
    plt.ylim(-1.0, 1.0)
    plt.show()

def colorline(
        x, y, z=None, cmap='copper', norm=plt.Normalize(0.0, 1.0),
        linewidth=3, alpha=1.0):
    """
    http://nbviewer.ipython.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb
    http://matplotlib.org/examples/pylab_examples/multicolored_line.html
    Plot a colored line with coordinates x and y
    Optionally specify colors in the array z
    Optionally specify a colormap, a norm function and a line width
    """

    # Default colors equally spaced on [0,1]:
    if z is None:
        z = np.linspace(0.0, 1.0, len(x))

    # Special case if a single number:
    # to check for numerical input -- this is a hack
    if not hasattr(z, "__iter__"):
        z = np.array([z])

    z = np.asarray(z)

    segments = make_segments(x, y)
    lc = mcoll.LineCollection(segments, array=z, cmap=cmap, norm=norm,
                              linewidth=linewidth, alpha=alpha)

    ax = plt.gca()
    ax.add_collection(lc)

    return lc

def make_segments(x, y):
    """
    Create list of line segments from x and y coordinates, in the correct format
    for LineCollection: an array of the form numlines x (points per line) x 2 (x
    and y) array
    """

    points = np.array([x, y]).T.reshape(-1, 1, 2)
    segments = np.concatenate([points[:-1], points[1:]], axis=1)
    return segments

multicolored_lines()

请注意,调用plt.plot数百次会导致性能下降.使用a LineCollection构建多色线段要快得多.