CODEWITHSUNDEEP
pythonarraysnumpy
johnnn123
johnnn123

Reputation: 75

Search a value between indexes of an array in Python

I have a sorted list(it contains more than 1000 cumulative elements). For example:

list = [1.236, 2.236, 5.1254, 9.125663, 9.9632, 15.1266, 18.254, 19.3315, 23.3265]

And I have a target number which is let's say 9.5. I want to find its position in list. So I want to see index 3rd and 4 (it should be between 3 (9.125663) and 4th (9.9632) indexes) as output without using a for loop.

Do you have an idea about it? Thank you.

Upvotes: 2

Views: 100

Answers (2)

Mustafa Aydın
Mustafa Aydın

Reputation: 18306

There is bisect module for this:

import bisect

the_list = [1.236, 2.236, 5.1254, 9.125663, 9.9632, 15.1266, 18.254, 19.3315, 23.3265]
val = 9.5
pos = bisect.bisect(the_list, val)

to get

>>> pos
4

You can then use (pos-1, pos) as (3, 4) (might need to check edge cases).

(Side note: bisect.bisect is synonymous to bisect.bisect_right so the returned pos will be right to the val if it is already in the list, e.g. if val was 5.1254, pos would be 3).

Upvotes: 3

Shubham Periwal
Shubham Periwal

Reputation: 2248

Used this link for the answer:

import numpy as np

def get_indices(array, value):
    array = np.array(array)

    # Subtract all values in array with value and get index of smallest value which would be the closest value
    idx = (np.abs(array - value)).argmin()

    #if closest value is greater than target value
    if(array[idx] > value):
        #+1 because you want "3rd and 4th" index, and python starts from 0
        print([idx+1, idx+2])

    #if closest value is lesser than target value
    elif(array[idx] < value):
        print([idx, idx+1])
    
    else:
        print([idx+1])

array = [1.236, 2.236, 5.1254, 9.125663, 9.9632, 15.1266, 18.254, 19.3315, 23.3265]
value = 9.5
get_indices(array, 9.5)  ## prints [3,4]
get_indices(array, 10.5) ## prints [4,5]

Upvotes: 2

Related Questions