Finding list indexes of numbers greater than a value

Question

How to get the index of a number in a python list if we have some condition:

    test_list=[1,5,7,11,20,26,89]
    # find index of number>13

Ans: 4 (index value)

Answer 1

You can also use numpy in the following way:

import numpy as np
x = np.array([1,5,7,11,20,26,89])
x[np.where(x>13)][0]  # 20

Note that you ask for the index but you wish the value, so in case you wish the index:

np.where(x>13)[0]  # array([4, 5, 6])

will give you all the indices the meets the condition

Answer 2

You can simply iterate through the list and break when you condition is true:

test_list = [1,5,7,11,20,26,89]
for i, value in enumerate(test_list):
    if value > 13:
        break

print(value)  # 20
print(i)      # 4

Answer 3

You can use the built-in index method. For example:

test_list = [1,5,7,11,20,26,89]
test_list.index(5)

will return 1. So you can use that in the following manner to get the desired result:

for i in test_list:
    if i > 13:
        print(test_list.index(i))

Edit: Added how to use the index method to meet the requirements of the question