pandas 解决 A value is trying to be set on a copy of a slice from a DataFrame的问题

stackoverflow 解决方案链接：
https://stackoverflow.com/questions/31468176/setting-values-on-a-copy-of-a-slice-from-a-dataframe?rq=1
出错代码：

def filter_date(date,df):
    df['start_time'] = pd.to_datetime(df['start_time'])  # 将数据类型转换为日期类型,可以直接获取相应年份的数据
    df = df.set_index('start_time')
    df_date = df[date]
    return df_date

修改后代码：

def filter_date(date,df):
    x = df.copy()
    x.loc[:,'start_time'] = pd.to_datetime(x.loc[:,'start_time'])  # 将数据类型转换为日期类型,可以直接获取相应年份的数据
    x = x.set_index('start_time')
    df_date = x[date]
    return df_date

主要做了两点修改：
1.copy()
2.采用loc提取列

实际操作中增加copy()即可解决问题

https://blog.csdn.net/zaishijizhidian/article/details/98207892