NumPy:以n为底的对数 [英] NumPy: Logarithm with base n

问题描述

从关于对数的numpy文档中，找到以底数 e 为底的对数的函数， 2 和10 :

From the numpy documentation on logarithms, I have found functions to take the logarithm with base e, 2, and 10:

import numpy as np
np.log(np.e**3) #3.0
np.log2(2**3)   #3.0
np.log10(10**3) #3.0

但是，如何以numpy为底数以 n (例如42)为底的对数?

However, how do I take the logarithm with base n (e.g. 42) in numpy?

推荐答案

使用使用 numpy.log来获取具有自定义基数的对数:

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]

请注意，默认情况下为np.log(np.e) == 1.0.

As you would expect, note that the default case of np.log(np.e) == 1.0.

提醒一下，对数基本更改的规则是:

As a reminder, the logarithm base change rule is:

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