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NumPy Logs


Logs

NumPy provides functions to perform log at the base 2, e and 10.

We will also explore how we can take log for any base by creating a custom ufunc.

All of the log functions will place -inf or inf in the elements if the log can not be computed.


Log at Base 2

Use the log2() function to perform log at the base 2.

Example

Find log at base 2 of all elements of following array:

import numpy as np

arr = np.arange(1, 10)

print(np.log2(arr))
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Note: The arange(1, 10) function returns an array with integers starting from 1 (included) to 10 (not included).


Log at Base 10

Use the log10() function to perform log at the base 10.

Example

Find log at base 10 of all elements of following array:

import numpy as np

arr = np.arange(1, 10)

print(np.log10(arr))
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Natural Log, or Log at Base e

Use the log() function to perform log at the base e.

Example

Find log at base e of all elements of following array:

import numpy as np

arr = np.arange(1, 10)

print(np.log(arr))
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Log at Any Base

NumPy does not provide any function to take log at any base, so we can use the frompyfunc() function along with inbuilt function math.log() with two input parameters and one output parameter:

Example

from math import log
import numpy as np

nplog = np.frompyfunc(log, 2, 1)

print(nplog(100, 15))
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