Python matplotlib 同じ軸にグラフをかく plt.legend()

参考：

qiita.com

コード：

import MySQLdb
from pylab import *

import sys
import numpy as np
import matplotlib.pyplot as plt
# new
from pandas import *

# A
minatoa = read_csv('minatoA.csv')
m = minatoa.groupby('avg_min_temp')['avg_sales'].mean()
# print (m)
plt.plot(m, "m.", label="A")

# B
tokyoresortb = read_csv('TokyoResortB.csv')
t = tokyoresortb.groupby(['avg_min_temp'])['avg_sales'].mean()
# print (t)
plt.plot(t, "g.", label="B")
# C
suburbresortb = read_csv('SuburbResortC.csv')
s = suburbresortb.groupby('avg_min_temp')['avg_sales'].mean()
# print (s)
plt.plot(s, "r.", label="C")
# D
centerd = read_csv('CenterinVicinityD.csv')
d = centerd.groupby('avg_min_temp')['avg_sales'].mean()
# print(d)
plt.plot(d, "k.", label="D")

plt.legend()