超过二十分类的饼图绘制如何调整比例

小比例不清
颜色的分配，希望有大佬提出解决办法
import matplotlib.pyplot as plt
import matplotlib
import csv
with open("lagou.csv",'r',encoding='utf-8-sig') as f:
reader=csv.reader(f)
city_=[]
for i in reader:
if i[1][0:3]=='石家庄':
i[1]=i[1][0:3]
else:
i[1]=i[1][0:2]
city_.append(i[1])
citySet=set(city_)
matplotlib.rcParams['font.family']='Kaiti'
plt.figure(figsize=(20, 20))
labels=citySet
data=[city_.count(i) for i in citySet]
explode=(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)
plt.pie(data,explode=explode,labels=labels,autopct='%1.1f%%',shadow=True,startangle=90,radius=40)
plt.axis('equal')
plt.show()

这种数据已经不适合用饼状图可视化了，可使使用柱状图