Create list of dates with increment of months and stop increments less than given date in pandas-CodePudding

Given data

Id	start Date	Frequency
1	10-10-2015	1
2	20–10-2016	2

I required in this format

Id	start Date	Frequency	Date1	Dat2	Date3	Date4
1	10-10-2015	1	10-10-2016	10-10-2017	10-10-2018
2	20–10-2016	2	20-04-2017	20-10-2017	20-04-2018	20-10-2018

If the frequency is 1 Date increments by 1 year and should not exceed 2018 year. If the frequency is 2 Date increments by 6 month and should not exceed 2018 year.

CodePudding user response：

You could apply pd.date_range on each row to create your required dates and join back to the original DataFrame:

df["start Date"] = pd.to_datetime(df["start Date"], format="%d-%m-%Y")
dates = df.apply(lambda x: pd.Series(pd.date_range(x["start Date"], 
                                                   "2018-12-31", 
                                                   freq=pd.DateOffset(months=12/x["Frequency"]))
                                                   ).add_prefix("Date"), axis=1)
output = df.join(dates.iloc[:,1:])

>>> output
   id start Date  Frequency      Date1      Date2      Date3      Date4
0   1 2015-10-10          1 2016-10-10 2017-10-10 2018-10-10        NaT
1   2 2016-10-20          2 2017-04-20 2017-10-20 2018-04-20 2018-10-20