Pandas Datetime: Calculate Number of Weeks Between Dates in Two Columns

datetime, pandas, python

Solution

see this link: http://pandas.pydata.org/pandas-docs/dev/timeseries.html#time-deltas

(df['Date2']-df['Date1']).apply(lambda x: x/np.timedelta64(1,'M'))

for numpy >=1.7 (see the link if you are using 1.6.1)

I am not sure what it will do with the fraction. (usually I would divide by `np.timedelta64(1,'D')` then divide by say 30 to make a fractional num of months (as a float)

Problem

Let's say I have a dataframe with two columns that contain dates, and I want to create a new columns whose value is the number of months between those dates. ``` >df Index Date1 Date2 1 2012/03/07 2013/03/16 2 2012/12/05 2012/12/25 3 2010/06/30 2013/05/19 4 2002/11/02 2011.06.08 df["Date1"]= pd.to_datetime(df["Date1"]) df["Date2"]= pd.to_datetime(df["Date2"]) ``` Date1 will always be before date2. My current method of doing this requires about 10 steps, and I'm pretty sure there's an easier way to do this. Thoughts?

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