Python+Matplotlib绘制双y轴图像的示例代码

import matplotlib.pyplot as plt
# 生成一组数据
x = range(7)
y1 = [2000, 1600, 3000, 6200, 7000, 9800, 11000]
y2 = [1]
for i in range(len(y1)):
    if i+1 == len(y1):
        break
    rate = round(y1[i+1]/y1[i] - 1, 2)
    y2.append(rate)

fig = plt.figure(figsize=(10, 8), facecolor='#ff33ff')
# 字体使用楷体
plt.rcParams['font.sans-serif'] = ['STKAITI']
plt.rcParams['axes.unicode_minus'] = False
# 背景色为cc00ff
plt.rcParams['axes.facecolor'] = '#cc00ff'
ax1 = fig.add_subplot(111)
plt.title('销售量及其增长率图示', color='#ffff00', fontsize=25, y=1.04)
plt.xticks(x, ['1月', '2月', '3月', '4月', '5月', '6月', '7月'], color='#ffff00', fontsize=15)
plt.xlabel('月份', color='#ff0033', fontsize=15)
plt.yticks(color='#B22222', fontsize=15)
ax1.bar(x, y1, color='#33ff66', label='left')
ax1.set_ylabel('销售量（件）', color='#66ff00', fontsize=20)
# 增加一条坐标轴
ax2 = ax1.twinx()
ax2.plot(x, y2, color='#3399ff', linestyle='--', marker='o', linewidth=2)
ax2.set_ylabel("增长率", color='#66ff00', fontsize=20)
ax2.tick_params(axis='y', color='green', labelsize=15, labelcolor='#B22222')
for a, b in zip(x, y2):
    plt.text(a, b+0.02, '%.2f' % b, ha='center', va='bottom', fontsize=15, color='red')
plt.show()

%matplotlib inline
import matplotlib.pyplot as plt
import random
import pandas as pd
import matplotlib as mpl
mpl.rcParams['font.sans-serif'] = ['FangSong']  # 指定默认字体
mpl.rcParams['axes.unicode_minus'] = False  # 解决保存图像是负号'-'显示为方块的问题
#数据准备
date=["一月","二月","三月","四月","五月","六月","七月","八月"]
sales=[random.randint(10000,25000) for i in range(8)]
cost=[int(i/100)-random.randint(1,20) for i in sales]
df=pd.DataFrame(data={"销量":sales,"成本":cost},index=date)
 
#绘制第一个Y轴
fig=plt.figure(figsize=(20,8),dpi=80)
ax=fig.add_subplot(111)
lin1=ax.plot(df.index,df["销量"],marker="o",label="sales")
ax.set_title("双Y轴图",size=20)
ax.set_xlabel("时间",size=18)
ax.set_ylabel("销量(件)",size=18)
for i,j in df["销量"].items():
    ax.text(i,j+20,str(j),va="bottom",ha="center",size=15)
 
#绘制另一Y轴    
ax1=ax.twinx()
lin2=ax1.plot(df.index,df["成本"],marker="o",color="red",label="cost")
ax1.set_ylabel("成本(元)",size=18)
 
#合并图例
lins=lin1+lin2
labs=[l.get_label() for l in lins]
ax.legend(lins,labs,loc="upper left",fontsize=15)
 
plt.show()