Python. How can I create a new column within a dataframe, which equals the number of days from 2 specific dates?

Question

I already have a list of dates in a dataframe. I would like to create a new column which calculates the number of days between these dates and 2020-06-26. First time asking question here, so apologize for phrasing poorly.

The dates column is currently an index column

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have a look at [pandas time deltas](https://pandas.pydata.org/pandas-docs/stable/user_guide/timedeltas.html) — FObersteiner, Jun 17 '20 at 07:35
This is a clear duplicate question from here https://stackoverflow.com/a/22132649/503835 please search SO before asking a question. — eNc, Jun 17 '20 at 07:41
Does this answer your question? [Add column with number of days between dates in DataFrame pandas](https://stackoverflow.com/questions/22132525/add-column-with-number-of-days-between-dates-in-dataframe-pandas) — eNc, Jun 17 '20 at 07:41

syrupstitious · Answer 1 · 2020-06-17T07:42:05.767

0

Use the datetime library and panda's apply function

from datetime import date

df = pd.DataFrame(
    {'date': [date(2020, 6, 10), date(2020, 6, 11), date(2020, 6, 12), date(2020, 6, 13)],
    })

def number_of_days_since(df):
    return date(2020,6, 26) - df['date']

df['days_since'] = df.apply(number_of_days_since, axis=1)

edited Jun 17 '20 at 07:42

answered Jun 17 '20 at 07:38

syrupstitious

1
2

you don't need a `lambda` here (also no `apply`); just `df['date'] - pd.to_datetime('2020-6-26')` - if you would use pandas' datetime instead of `datetime.date`... – FObersteiner Jun 17 '20 at 07:41

score 0 · Answer 2 · answered Jun 17 '20 at 07:39

You can make these two columns as datetime and just subtract them it will create new column with number of days(difference between two dates).

df['Date1'] = pd.to_datetime(df['Date1']) 
df['Date2'] = pd.to_datetime(df['Date2']) 
df ['days'] = df['Date1'] - df['Date2']

Python. How can I create a new column within a dataframe, which equals the number of days from 2 specific dates?

2 Answers2