CODEWITHSUNDEEP
pythonpandas
pheno
pheno

Reputation: 455

Finding Date difference in list of dates [Pandas]

Assuming the following dataset has sorted list of dates:

dates=pd.DataFrame(data={'client':['1','2'],
                         'date':[['2012-3-10','2012-3-11','2012-3-12','2012-3-13','2012-3-14'],
                                 ['2012-3-12','2012-3-13','2012-3-16','2012-3-23']]})

sample dataset

I want to find the average date difference in terms of days So, For eg, for Client '2', Average Timelag would be 2.75

Upvotes: 1

Views: 783

Answers (2)

Stefan
Stefan

Reputation: 42875

Starting with:

  client                                               date
0      1  [2012-3-10, 2012-3-11, 2012-3-12, 2012-3-13, 2...
1      2       [2012-3-12, 2012-3-13, 2012-3-16, 2012-3-23]

You could

dates.groupby('client')['date'].apply(lambda x: [i / np.timedelta64(1, 'D') for i in np.diff([pd.to_datetime(c) for c in x])[0]])

to get the timedelta in days:

client
1    [1.0, 1.0, 1.0, 1.0]
2         [1.0, 3.0, 7.0]

or 

dates.groupby('client')['date'].apply(lambda x: np.mean([i / np.timedelta64(1, 'D') for i in np.diff([pd.to_datetime(c) for c in x])[0]]))

for the mean:

client
1    1.000000
2    3.666667

Upvotes: 2

PetMetz
PetMetz

Reputation: 85

This is a repeat of:

Difference between two dates?

It looks like you can use the datetime modules to parse the date and/or time strings you're importing into objects which support algebra.

https://docs.python.org/2/library/datetime.html

Cheers

Upvotes: 0

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