CODEWITHSUNDEEP
pandasdataframefor-loop
PaulCoder
PaulCoder

Reputation: 27

Make a for loop for a dataframe to substract dates and put it in a variable

I have a dataframe that looks like this with a lot of products

Product Start Date
00001 2021/08/10
00002 2021/01/10

I want to make a cycle so that it goes from product to product subtracting three months from the date and then putting it in a variable, something like this. date[]=''

for dataframe in i:
    date['3monthsbefore']=i['start date']-3 months
    date['3monthsafter']=i['start date']+3 months
    date['product']=i['product']
    "Another process with those variables"

And then concat all this data in a dataframe I´m a little bit lost, I want to do this because I need to use those variables in another process, so I't is possible to do this?.

Upvotes: 0

Views: 40

Answers (1)

C. Braun
C. Braun

Reputation: 5201

Using pandas, you usually don't need to loop over your DataFrame. In this case, you can get the 3 months before/after for all rows pretty simply using pd.DateOffset:

df["Start Date"] = pd.to_datetime(df["Start Date"])
df["3monthsbefore"] = df["Start Date"] - pd.DateOffset(months=3)
df["3monthsafter"] = df["Start Date"] + pd.DateOffset(months=3)

This gives:

  Product Start Date 3monthsbefore 3monthsafter
0   00001 2021-08-10    2021-05-10   2021-11-10
1   00002 2021-01-10    2020-10-10   2021-04-10

Data:

df = pd.DataFrame({"Product": ["00001", "00002"], "Start Date": ["2021/08/10", "2021/01/10"]})

Upvotes: 3

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