I have two datetimes between which I would like to generate regular intervals of 4 hours (excluding the last interval, which can be less than 4 hours if there are less than 4 hours between the previous timestamp and end).
I am stuck on interval generation with pandas.date_range, which only returns the end timestamp. For example:
import pandas
from datetime import datetime
start = datetime(2021, 4, 2, 20, 40, 0)
end = datetime(2021, 4, 4, 18, 20, 0)
dates = pandas.date_range(start=end, end=end, freq='4H')
dates
DatetimeIndex(['2021-04-04 18:20:00'], dtype='datetime64[ns]', freq='4H')
The aim is to generate a list of datetime pairs such as:
[['2021-04-02 20:40:00', '2021-04-03 00:40:00'], ['2021-04-03 00:40:00', '2021-04-03 04:40:00']...['2021-04-04 16:40:00', '2021-04-04 18:20:00']] #last pair can be cut off by `end`.
What am I doing wrong in the syntax and how would one go about generating a paired list of intervals from using pandas.date_range ?
There was a typo (start=end) that caused dates to have only 1 value.
But fixing the typo only gives you a flat range of dates. If you want those nested pairs, you could shift dates by 4 hours and zip():
dates = pandas.date_range(start=start, end=end, freq='4H')
shift = dates + pandas.Timedelta(hours=4)
pairs = list(zip(dates, shift))
# [(Timestamp('2021-04-02 20:40:00', freq='4H'),
# Timestamp('2021-04-03 00:40:00', freq='4H')),
# (Timestamp('2021-04-03 00:40:00', freq='4H'),
# Timestamp('2021-04-03 04:40:00', freq='4H')),
# (Timestamp('2021-04-03 04:40:00', freq='4H'),
# Timestamp('2021-04-03 08:40:00', freq='4H')),
# ...
Or for a list of lists instead of list of tuples:
pairs = list(map(list, zip(dates, shift)))