CODEWITHSUNDEEP
pythonnumpypandas
Tingiskhan
Tingiskhan

Reputation: 1345

Find indices based on datetime

Assume that I have the following data

import numpy as np, pandas as pd

numids = 3
start, end = datetime.datetime(2015, 1, 1), datetime.datetime(2016, 2, 15)
date_list = np.tile(pd.date_range(start, end, freq='B'), numids)

How do I find all indices where , say, date_list == datetime.datetime(2015, 3, 31)? This should be an easy problem, but I can't seem to figure it out. Thanks, Tingis

Edit If we take a simple example and set numids to 1 and the date of interest to be datetime.datetime(2015, 1, 1), I would like to get the index 1. Or a list [True, False, False, ..., False].

Edit 2 Now, I try to just loop through the array and calculate the difference in days, such as

for date in date_list:
    print(date - datetime.datetime(2015, 1, 12))

However, this gives me an error that I've never seen

TypeError: ufunc subtract cannot use operands with types dtype('<M8[ns]') and dtype('O')

Upvotes: 1

Views: 7650

Answers (1)

Anand S Kumar
Anand S Kumar

Reputation: 90989

You can try this -

np.where(date_list == np.datetime64(datetime.datetime(2015, 3, 31)))
>>> (array([ 63, 356, 649], dtype=int64),)

Upvotes: 3

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