Python Matplotlib绘图

Posted 2021-01-26 xibuhaohao

一、安装Matplotlib

pip3.5 install matplotlib

二、保存图片

保存的时候要将plt.savefig(\'./test2.jpg\')放到了plt.show()之后，否则保存的为空白图片。

先保存，后展示

import matplotlib.pyplot as plt

name_list = [\'Monday\',\'Tuesday\',\'Friday\',\'Sunday\']

num_list = [1.5,0.6,7.8,6]
num_list1 = [1,2,3,1]

x =list(range(len(num_list)))

total_width, n = 0.8, 2

width = total_width / n

plt.bar(x, num_list, width=width, label=\'boy\',fc = \'y\')

for i in range(len(x)):

    x[i] = x[i] + width

plt.bar(x, num_list1, width=width, label=\'girl\',tick_label = name_list,fc = \'r\')

plt.legend()

plt.savefig(\'./test.jpg\')

plt.show()

三、连接数据库动态展示

代码如下：

# -*- coding: utf-8 -*-

import  pymysqlimport matplotlib.pyplot as plt

db=pymysql.connect(host="master",user=\'root\',passwd="123456",port=3306,db="lagou",charset=\'utf8\')

cursor=db.cursor()#获取一个游标

sql="select city,need from citys"

cursor.execute(sql)

result=cursor.fetchall() #result为元组

#将元组数据存进列表中

city=[]

need=[]

for x in result:

    city.append(x[0])

    need.append(x[1])

#直方图

plt.bar(range(len(need)), need, color=\'steelblue\', tick_label=city)

plt.xlabel("城市名")

plt.ylabel("数量")

plt.title("城市职位需求图")

for  x,y in enumerate(need):

    plt.text(x-0.4, y+0.4, \'%s\' % y)

plt.show()

cursor.close()#关闭游标

db.close()#关闭数据库

四、