获取最接近给定日期的日期列表的索引

Question

I have the following date :

date=np.datetime64 (2019-12-15)

then I have a list of np.datetime64 dates:

['2018-01-01','2019-01-01','2019-04-12','2019-12-01']

I would like to obtain the index from the list which is closest to my date.

The desired output would be 3 which is the position of the list of dates closer to my date.

I am not able to provide an example given I dont know how to test my issue.

I can only think of an assert.AlmostEqual but I am not sure on how to reflect it on an example.

Answer 1

Express your list as a numpy array and just find the index of the smallest difference using np.argmin :

import numpy as np

date = np.datetime64('2019-12-15')
array = np.array(['2018-01-01','2019-01-01','2019-04-12','2019-12-01'],
                 dtype=np.datetime64)

result = np.argmin(np.abs(array - date))

Answer 2

According to the datetime documentation, you can calculate timedeltas by simply subtracting the dates.

#Set date
date=np.datetime64 ('2019-12-15')


#Create list of strings holding date values
l = ['2018-01-01','2019-01-01','2019-04-12','2019-12-01']

#Convert strings to numpy dates 
l = [numpy.datetime64(x) for x in l]

#For each value in date list, subtract from start date. 
delta = [abs(x - date) for x in l]

#Set minimum index (see link below)
idx = np.argmin(d)

This will output 3 .

Min index code obtained from here