Python NumPy：以 n 为底的对数
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NumPy: Logarithm with base n
提问by Banana
From the numpy documentation on logarithms, I have found functions to take the logarithm with base e, 2, and 10:
从关于 logarithms的numpy 文档中，我找到了以e、2和10为底取对数的函数：
import numpy as np
np.log(np.e**3) #3.0
np.log2(2**3) #3.0
np.log10(10**3) #3.0
However, how do I take the logarithm with base n(e.g. 42) in numpy?
但是，如何在 numpy 中取以n（例如 42）为底的对数？
采纳答案by Banana
To get the logarithm with a custom base using math.log:
要使用自定义基数获取对数，请使用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:
要使用自定义基数获取对数，请使用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]
As you would expect, note that the default case of np.log(np.e) == 1.0.
正如您所料，请注意np.log(np.e) == 1.0.
As a reminder, the logarithm base changerule is:
提醒一下，对数基数变化规则是：
