如何将整列转换为日期格式？

Question

I tried this to remove the unwanted characters but it is not working

from datetime import datetime

dates = []

for i in data.Date:
    date_time_str = str(data.Date[i])
    date_time_str = date_time_str.replace("M ","")
    date1 = date_time_str.replace(".","")
    dates.append(date1)

print(dates)

Answer 1

Use pd.to_datetime and give a correct format string for your data ( 'M %m.%Y' ):

import pandas as pd

data = pd.DataFrame( {"Code":[114, 115, 116, 117], 
                      "Date":["M 02.2017", "M 03.2018", "M 04.2019", "M 05.2020",]})

print(data)

# simply use the correct format string for your data here
data["asDate"] = pd.to_datetime(data["Date"], format = "M %m.%Y") 
print(data)

Output:

   Code       Date
0   114  M 02.2017
1   115  M 03.2018
2   116  M 04.2019
3   117  M 05.2020

   Code       Date     asDate
0   114  M 02.2017 2017-02-01
1   115  M 03.2018 2018-03-01
2   116  M 04.2019 2019-04-01
3   117  M 05.2020 2020-05-01

To get just the dates as list use

dates_1 = list(data["asDate"]) # contains <class 'numpy.datetime64'> and
dates_2 = list(data["asDate"].values) # <class 'pandas._libs.tslibs.timestamps.Timestamp'>

Answer 2

Assuming your dates are always prefaced with 'M ' (meaning that the actual date starts at position 2 in the string):

df['date'] = df['date'].apply(lambda x: pd.to_datetime(x[2:], format = '%m.%Y'))