Add column with number of days between dates in DataFrame pandas

Question

I want to subtract dates in  A  from dates in  B  and add a new column with the difference   df           A        B one 2014-01-01  2014-02-28  two 2014-02-03  2014-03-01   I ve tried the following  but get an error when I try to include this in a for loop     import datetime date1 df  A   0  date2 df  B   0  mdate1   datetime datetime strptime date1    Y- m- d   date   rdate1   datetime datetime strptime date2    Y- m- d   date   delta     mdate1 - rdate1  days print delta   What should I do

User · Answer

How about this     times  days since     max list df index values     times  days since     times  days since   - times  months     times

User · Answer

Assuming these were datetime columns  if they re not apply to datetime  you can just subtract them   df  A     pd to datetime df  A    df  B     pd to datetime df  B     In  11   df dtypes    if already datetime64 you don t need to use to datetime Out 11   A    datetime64 ns  B    datetime64 ns  dtype  object  In  12   df  A   - df  B   Out 12   one   -58 days two   -26 days dtype  timedelta64 ns   In  13   df  C     df  A   - df  B    In  14   df Out 14                A          B        C one 2014-01-01 2014-02-28 -58 days two 2014-02-03 2014-03-01 -26 days   Note  ensure you re using a new of pandas  e g  0 13 1   this may not work in older versions

User · Answer

A list comprehension is your best bet for the most Pythonic  and fastest  way to do this    int i days  for i in  df B - df A      i will return the timedelta e g   -58 days   i days will return this value as a long integer value e g  -58L  int i days  will give you the -58 you seek    If your columns aren t in datetime format  The shorter syntax would be  df A   pd to datetime df A

User · Answer

To remove the  days  text element  you can also make use of the dt   accessor for series  https   pandas pydata org pandas-docs stable generated pandas Series dt html  So    df   A   B      df   A   B    apply pd to datetime   if conversion required df  C      df  B   - df  A    dt days   which returns                A          B   C one 2014-01-01 2014-02-28  58 two 2014-02-03 2014-03-01  26

[python] Add column with number of days between dates in DataFrame pandas

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