Getting the closest date to a given date

Question

Given this base date:

base_date = \"10/29 06:58 AM\"

I want to find a tuple within the list that contains the closest date to the bas

Answer 1

I was looking up this problem and found some answers, most of which check all elements. I have my dates sorted (and assume most people do), so if you do as well, use numpy:

import numpy as np
// dates is a numpy array of np.datetime64 objects
dates = np.array([date1, date2, date3, ...], dtype=np.datetime64)
timestamp = np.datetime64('Your date')
np.searchsorted(dates, timestamp)

searchsorted uses binary search, which uses the fact the dates are sorted, and is thus very efficient. If you use pandas, this is possible:

dates = df.index # df is a DatetimeIndex-ed dataframe
timestamp = pd.to_datetime('your date here', format='its format')
np.searchsorted(dates, timestamp)

The function returns the index of the closest date (if the searched date is included in dates, its index is returned [if that isn't wanted, use side='right' as an argument into the function]), so to get the date do this:

dates[np.searchsorted(dates, timestamp)]