#範例3-6：如何把圖形存檔成p3-6.png
#指令：plt.savefig('p3-6.png')
#注意：這是matplotlib.pyplot函數庫指令，故必須先import

import pandas as pd
import matplotlib.pyplot as plt

df = pd.DataFrame({
    'name':['john','mary','peter','jeff','bill','lisa','jose'],
    'age':[23,78,22,19,45,33,20],
    'gender':['M','F','M','M','M','F','M'],
    'state':['california','dc','california','dc','california','texas','texas'],
    'num_children':[2,0,0,3,2,1,4],
    'num_pets':[5,1,0,5,2,2,3]
})
# gca 代表取得目figure前坐標軸 axis（gca = get current figure）
ax1 = plt.gca()

#顯示每人寵物數量（座標軸 = ax1)
df.plot(ax=ax1, kind='line',x='name',y='num_pets',color='red')
#顯示每人的小孩數量（座標軸 = ax1)
df.plot(ax=ax1, kind='line',x='name', y='num_children',color='green')
#兩個圖組，一起存檔
#plt.show()
plt.savefig('p3-6.png')