scipy.special.logit — SciPy v1.15.2 Manual (original) (raw)

scipy.special.logit(x, out=None) = <ufunc 'logit'>#

Logit ufunc for ndarrays.

The logit function is defined as logit(p) = log(p/(1-p)). Note that logit(0) = -inf, logit(1) = inf, and logit(p) for p<0 or p>1 yields nan.

Parameters:

xndarray

The ndarray to apply logit to element-wise.

outndarray, optional

Optional output array for the function results

Returns:

scalar or ndarray

An ndarray of the same shape as x. Its entries are logit of the corresponding entry of x.

Notes

As a ufunc logit takes a number of optional keyword arguments. For more information see ufuncs

Added in version 0.10.0.

Examples

import numpy as np from scipy.special import logit, expit

logit([0, 0.25, 0.5, 0.75, 1]) array([ -inf, -1.09861229, 0. , 1.09861229, inf])

expit is the inverse of logit:

expit(logit([0.1, 0.75, 0.999])) array([ 0.1 , 0.75 , 0.999])

Plot logit(x) for x in [0, 1]:

import matplotlib.pyplot as plt x = np.linspace(0, 1, 501) y = logit(x) plt.plot(x, y) plt.grid() plt.ylim(-6, 6) plt.xlabel('x') plt.title('logit(x)') plt.show()