pandas plot

如果id不是字符串型需要先轉化爲字符串才行，title加標題，subplots設置日期斜着顯示

pp = pd.DataFrame({"id":["1001", "1001", "1001", 
                    "1002", "1002", "1002", '1002',
                    "1003", "1003", "1003", '1003', '1003'],
             "day":["2018-7-15", "2018-7-16","2018-7-18",
                    "2018-7-15", "2018-7-16","2018-7-18", "2018-7-19",
                    "2018-7-15", "2018-7-16","2018-7-18", "2018-7-19","2018-7-22"],
             "kg":[68, 64, 56, 
                   68, 64, 56, 78,
                  68, 64, 56,56, 65]})
pp = pp.set_index('day')
pp.groupby("id").plot()

for name, group in pp.groupby("id"):
    group.plot(title="id:"+name,subplots=True)