我会创建自定义线条以显示在您的图例中。您可以通过保存每个绘图命令的输出来解决此问题（线图返回一个 matplotlib.lines.Line2D 对象，该对象存储线型、标记样式、颜色等）。然后，您可以遍历保存的行并创建新的Line2D 对象，将两条线的属性与相同的颜色组合在一起。将这些新的Line2D 对象保存在一个列表中，比如handles，然后您可以将该列表传递给ax.legend() 调用：
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.lines import Line2D
Vs = np.array([0.5, 1, 1.5, 2])
Xs = np.array([[ 0.5, 0.2, 0.7],
[ 0.5, 0.3, 0.9],
[ 0.5, 0.5, 0.4],
[ 0.5, 0.7, 0.4],
[ 0.5, 0.9, 0.7],
[ 1, 0.15, 0.9],
[ 1, 0.35, 0.6],
[ 1, 0.45, 0.6],
[ 1, 0.67, 0.5],
[ 1, 0.85, 0.9],
[ 1.5, 0.1, 0.9],
[ 1.5, 0.3, 0.7],
[ 1.5, 0.76, 0.3],
[ 1.5, 0.98, 0.4],
[ 2, 0.21, 0.5],
[ 2, 0.46, 0.4],
[ 2, 0.66, 0.3],
[ 2, 0.76, 0.5],
[ 2, 0.88, 0.4],
[ 2, 0.99, 0.4]])
f, axs = plt.subplots(1, 1, figsize=(2.5,3))
#-------------------------------------
axs.set_xlim(0.38,1.0)
axs.set_ylim(0.0,4.0)
colors = plt.cm.gist_ncar(np.linspace(0,1,max(Vs)+3))
##saving the Line2D objects:
lines = []
points = []
for idx,Val in enumerate(Vs):
point, = axs.plot(
Xs[Xs[:,0] == Val ,1], Xs[Xs[:,0] == Val ,2],'s',
label=r"$Y={}$".format(Val), ms=3, color=colors[idx]
)
line, = axs.plot(
Xs[Xs[:,0] == Val ,1], Xs[Xs[:,0] == Val ,2]*Val/0.3,'-',
label=r"$Y={}$".format(Val), ms=3, color=colors[idx]
)
points.append(point)
lines.append(line)
axs.set_ylim(0.0,4.0)
axs.set_ylabel(r"$Y$ ", labelpad=2)
axs.set_xlabel(r"$X$ ", labelpad=2)
axs.set_yticks([0,0.5,1.0,1.5,2.0, 2.5, 3.0, 3.5, 4.0])
axs.set_xticks([0,0.5,1.0])
#axs.legend(fontsize=6, loc=2, numpoints = 1, labelspacing=0.2,handletextpad=0.2, frameon=False)
#f.savefig("tmp.pdf")
##generating the legend handles, with linestyle, markerstyle, color, and label
##copied from the plotted lines:
handles = [
Line2D(
[],[], marker=point.get_marker(), linestyle=line.get_linestyle(),
color = line.get_color(),
label = line.get_label(),
) for line, point in zip(lines,points)
]
##passing handles as argument to the `legend()` call:
axs.legend(
handles=handles,
fontsize=6, loc=2, numpoints = 1, labelspacing=0.2,
handletextpad=0.2, frameon=False,
)
plt.show()
生成的图片如下所示：
编辑：
按照问题中链接的示例，可以设计一个处理程序对象来生成所需的图例句柄。将上述代码的最后一部分替换为以下内容：
##a dedicated class that holds the lines to be included in the legend entry
class LineContainer:
def __init__(self, *args):
args = [line for line in args if isinstance(line,Line2D)]
if len(args) < 0:
raise ValueError('At least one line must be passed')
self._lines = list(args)
def get_lines(self):
return self._lines
def get_label(self):
##assuming here that all lines have the same label
return self._lines[0].get_label()
##adapted from https://stackoverflow.com/a/31530393/2454357
class data_handler(object):
def legend_artist(self, legend, orig_handle, fontsize, handlebox):
scale = fontsize / 22
x0, y0 = handlebox.xdescent, handlebox.ydescent
width, height = handlebox.width, handlebox.height
##use these two lines to control the lengths of the individual line
##segments and the spacing between them:
##width for individual artists
l = 0.7*width/len(orig_handle.get_lines())
##distance between individual artists
l0 = 0.3*width/len(orig_handle.get_lines())
result = []
for i, line in enumerate(orig_handle.get_lines()):
new_line = Line2D([],[])
new_line.update_from(line)
##if no linestyle is defined, plot only the marker:
if new_line.get_linestyle() in ['None', None]:
new_line.set_data(
[x0+l*(i+0.5)], [y0+height/2]
)
##else plot markers and lines:
else:
new_line.set_data(
[x0+l*i+l0/2, x0+l*(i+1)-l0/2],
[y0+height/2, y0+height/2]
)
new_line.set_transform(handlebox.get_transform())
handlebox.add_artist(new_line)
result.append(new_line)
return result
##generating the handles
handles = [
LineContainer(line, point) for line, point in zip(lines, points)
]
axs.legend(
handles = handles,
handler_map={LineContainer: data_handler()},
fontsize=6, loc=2, numpoints = 1, labelspacing=0.2,
handletextpad=0.2, frameon=False,
)
plt.show()
给出以下图像：