CODEWITHSUNDEEP
pythonlistsortingdatetime
tda
tda

Reputation: 2133

Find the nearest 5 dates from a list in Python

I have a list of datetime objects and want to find the closest 5 (or 6 or 7 etc.) dates that correspond with my specified date.

For instance: 

datelist
>>>> [datetime.date(2017, 3, 4), datetime.date(2017, 3, 6), datetime.date(2017, 3, 12), datetime.date(2017, 3, 27), datetime.date(2017, 3, 27), datetime.date(2017, 3, 29), datetime.date(2017, 3, 29), datetime.date(2017, 4, 2), datetime.date(2017, 4, 4)]

If I type:

my_date = datetime.date(2017, 4, 2)
nearest_list = find_nearest(datelist, my_date)  # Functionality I want!

print nearest_list
>>>> [datetime.date(2017, 3, 27), datetime.date(2017, 3, 29), datetime.date(2017, 3, 29), datetime.date(2017, 4, 2), datetime.date(2017, 4, 4)]

I should receive a list of the nearest 5 dates.

I know that I could find the nearest date and take the two list elements either side of this (as datelist is sorted) but this is difficult when the nearest date may be the first or last element (i.e. no items before or after, respectively).

Upvotes: 2

Views: 112

Answers (1)

jpp
jpp

Reputation: 164623

You can use sorted with a custom function:

res = sorted(datelist, key=lambda x: abs(x-my_date))[:5]

[datetime.date(2017, 4, 2),
 datetime.date(2017, 4, 4),
 datetime.date(2017, 3, 29),
 datetime.date(2017, 3, 29),
 datetime.date(2017, 3, 27)]

Upvotes: 6

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