check if array of dates is within range of dates in python

Andrew Zac 0
Viewed 28

I have an array of dates that should be between 09-2021 and 09-2022. How do I check if every single one of the dates is in the range?

e.g Below are some of the dates within the array

calendar202109['date'].dt.date.unique()
array([datetime.date(2021, 9, 16), datetime.date(2021, 9, 17),
       datetime.date(2021, 9, 18), datetime.date(2021, 9, 19),
       datetime.date(2022, 9, 15)], dtype=object)
date range pandas python
2 Answers

Without the aid of pandas you could just do this:

from datetime import date

list_ = [date(2021, 9, 16),
         date(2021, 9, 17),
         date(2021, 9, 18),
         date(2021, 9, 19),
         date(2022, 9, 15)]

lo_bound = date(2021, 9, 1)
hi_bound = date(2022, 8, 31)

for d in list_:
    if not lo_bound <= d <= hi_bound:
        print(d, 'Out of range')

Output:

2022-09-15 Out of range
Vlad0

You can use numpy directly for that:

a = array([datetime.date(2021, 9, 16), datetime.date(2021, 9, 17),
           datetime.date(2021, 9, 18), datetime.date(2021, 9, 19),
           datetime.date(2022, 9, 15)], dtype=object)

((a > pd.Timestamp('2021-09-01')) & (a < pd.Timestamp('2022-08-31'))).all()

output: False

To identify the outliers:

m = ((a > datetime.date(2021, 9, 1)) & (a < pd.Timestamp('2022-08-31')))

a[~m]

output: array([datetime.date(2022, 9, 15)], dtype=object)

NB. using here pd.Timestamp('2021-09-01') as a convenience, you can use datetime.date(2021, 9, 1) instead.

mozway0
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