Replace values from column in Pandas dataframe

Question

Inside my Pandas dataframe, my 'Date' columns have strings of the format mm/dd/yyyy . What I want to do is convert them into YYYY-dd-mm .

df = pd.read_csv(csv_file, header=1)

date_list = df['Date'].values
for item in date_list:
    item = pd.to_datetime(item).strftime('%Y-%m-%d')
    print(item)

This code converts the dates successfully, but the dataframe is not changed. How can I make it change the dataframe with the new format?

Answer 1

更好的方法是将to_datetime与所有列值一起使用，然后将Series.dt.strftime与更改格式更改为%Y-%d-%m ：

df['Date'] = pd.to_datetime(df['Date']).dt.strftime('%Y-%d-%m')