将图例添加到 LineCollection 图中

这是与中给出的答案相关的派生问题根据颜色图设置线条颜色 https://stackoverflow.com/questions/19868548/set-line-colors-according-to-colormap其中建议了一个很好的解决方案，根据颜色条绘制多条带有颜色的线（请参见下面的代码和输出图像）。

我有一个列表，存储与每条绘制线关联的字符串，如下所示：

legend_list = ['line_1', 'line_2', 'line_3', 'line_4']

我想将这些字符串作为图例添加到绘图右上角的框中（其中第一个字符串对应于第一条绘制线等）。我怎么能这样做呢？

我愿意不使用LineCollection如果有必要，但我需要保留颜色条和与其关联的每条线的颜色。

代码和输出

import numpy
import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection

# The line format you curently have:
lines = [[(0, 1, 2, 3, 4), (4, 5, 6, 7, 8)],
         [(0, 1, 2, 3, 4), (0, 1, 2, 3, 4)],
         [(0, 1, 2, 3, 4), (8, 7, 6, 5, 4)],
         [(4, 5, 6, 7, 8), (0, 1, 2, 3, 4)]]

# Reformat it to what `LineCollection` expects:
lines = [zip(x, y) for x, y in lines]

z = np.array([0.1, 9.4, 3.8, 2.0])

fig, ax = plt.subplots()
lines = LineCollection(lines, array=z, cmap=plt.cm.rainbow, linewidths=5)
ax.add_collection(lines)
fig.colorbar(lines)

# Manually adding artists doesn't rescale the plot, so we need to autoscale
ax.autoscale()

plt.show()

如果你的行数很少，@unutbu 的答案是正确的方法。 （如果您想添加图例，您大概会这样做！）

不过，只是为了显示其他选项，您仍然可以使用LineCollection，您只需使用“代理艺术家”作为图例：

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection
from matplotlib.lines import Line2D

# The line format you curently have:
lines = [[(0, 1, 2, 3, 4), (4, 5, 6, 7, 8)],
         [(0, 1, 2, 3, 4), (0, 1, 2, 3, 4)],
         [(0, 1, 2, 3, 4), (8, 7, 6, 5, 4)],
         [(4, 5, 6, 7, 8), (0, 1, 2, 3, 4)]]

# Reformat it to what `LineCollection` expects:
lines = [tuple(zip(x, y)) for x, y in lines]

z = np.array([0.1, 9.4, 3.8, 2.0])

fig, ax = plt.subplots()
lines = LineCollection(lines, array=z, linewidths=5,
                       cmap=plt.cm.rainbow, norm=plt.Normalize(z.min(), z.max()))
ax.add_collection(lines)
fig.colorbar(lines)

# Manually adding artists doesn't rescale the plot, so we need to autoscale
ax.autoscale()

def make_proxy(zvalue, scalar_mappable, **kwargs):
    color = scalar_mappable.cmap(scalar_mappable.norm(zvalue))
    return Line2D([0, 1], [0, 1], color=color, **kwargs)
proxies = [make_proxy(item, lines, linewidth=5) for item in z]
ax.legend(proxies, ['Line 1', 'Line 2', 'Line 3', 'Line 4'])

plt.show()