python - 切换图例顺序

Question

我一直在制作一个绘制氢原子能级的图表，虽然从技术上讲，所附第一个图表中显示的所有内容都是正确的，但我试图切换右侧图例的顺序，以便红线位于底部和仍然标记为 n=1。当我在图例上切换范围时，它使图形看起来像第二张图片，其中 n=1 位于底部，但没有一种颜色正确对应。关于如何在保持订单正确的同时更改订单的任何建议？我的代码如下

import numpy
import math
import os
import matplotlib.pyplot as plt
import pandas as pd
colors = ['#e6194b', '#3cb44b', '#ffe119', '#4363d8', '#f58231', '#911eb4', '#46f0f0', '#f032e6', '#bcf60c', '#fabebe', '#008080', '#e6beff', '#9a6324', '#fffac8', '#800000', '#aaffc3', '#808000', '#ffd8b1', '#000075', '#808080', '#ffffff', '#000000']
#Values the user can edit
n_int = 6 #The inital energy level (must be greater than n_final)
n_final = 5 #The final energy level 
n_max = 11 #This is the highest energy level you want to look at plus 1 (ie: for energy levels 1-10 "n" would be 11)

# Energy level diagram for the Hydrogen Atom (all energy levels)
m_e = 9.1093837015* 10 ** -31 # kg
e = 1.602176634* 10 ** -19 # C
vp = 1.113* 10 ** -10 # C^2 / Jm
h = 6.62607015 * 10 ** -34 # J*s
h_bar = h/(2 * math.pi)  
n_min = 1
n = numpy.linspace(n_min, n_max, n_max-n_min)

#Equation broken down
p1 = m_e * e **4
p2 = 2 * vp ** 2 
p3 = h_bar ** 2
p4 = n ** 2
p5 = p2*p3*p4
e_lv = - p1/p5 #Outputs the values for the energy levels you inputed

max_bound = -numpy.log10(numpy.abs(y_big))
e_lv_math = -numpy.log10(numpy.abs(e_lv_i))
e_lv_math2 = -numpy.log10(numpy.abs(e_lv_f))
d_e_math = e_lv_math2-e_lv_math

inc = 0
for big_int in e_lv:
    x_big = range(0,n_max)
    y_big = [big_int]*n_max
    plt.plot(x_big, -numpy.log10(numpy.abs(y_big)), color = colors[inc])
    inc+=1
    plt.xticks([])
    plt.yticks([])
    plt.ylabel('Relative Energy Levels')
    plt.arrow(4.5, e_lv_math, 0, d_e_math, width = 0)
    plt.tight_layout()
plt.legend(range(n_max,0,-1), loc="center right", bbox_to_anchor = (1.2,.5), title = "n=")

标签： pythonmatplotlibplotlegend

Answer 1

如果要反转图例行的顺序并保持标签不变，则必须反转图例的顺序handles。
您应该从您正在绘制的轴获取handles和：labels

handles, labels = ax.get_legend_handles_labels()

然后将它们传递给legend，颠倒 的顺序handles：

ax.legend(handles = handles[::-1], labels = labels)

工作代码示例

import matplotlib.pyplot as plt
    

fig, ax = plt.subplots(1, 2)

ax[0].plot([0, 1], [1, 1], color = 'red', label = 'line 1')
ax[0].plot([0, 1], [2, 2], color = 'blue', label = 'line 2')
ax[0].plot([0, 1], [3, 3], color = 'gold', label = 'line 3')

ax[0].legend(frameon = True, loc = 'upper left', bbox_to_anchor = (1.05, 1))

ax[1].plot([0, 1], [1, 1], color = 'red', label = 'line 1')
ax[1].plot([0, 1], [2, 2], color = 'blue', label = 'line 2')
ax[1].plot([0, 1], [3, 3], color = 'gold', label = 'line 3')

handles, labels = ax[1].get_legend_handles_labels()
ax[1].legend(handles = handles[::-1], labels = labels, frameon = True, loc = 'upper left', bbox_to_anchor = (1.05, 1))

plt.tight_layout()

plt.show()