NumPy: Logarithm with base n

Solution 1:

To get the logarithm with a custom base using math.log:

import math
number = 74088  # = 42^3
base = 42
exponent = math.log(number, base)  # = 3

To get the logarithm with a custom base using numpy.log:

import numpy as np
array = np.array([74088, 3111696])  # = [42^3, 42^4]
base = 42
exponent = np.log(array) / np.log(base)  # = [3, 4]

Which uses the logarithm base change rule:

\log_b(x)=\log_c(x)/\log_c(b)