scipy.special.logit — SciPy v1.16.0 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.

logit has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

See Support for the array API standard for more information.

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()