# yasa.transition_matrix

yasa.transition_matrix(hypno)[source]

Create a state-transition matrix from an hypnogram.

New in version 0.1.9.

Parameters
hypnoarray_like

Hypnogram. The dtype of hypno must be integer (e.g. [0, 2, 2, 1, 1, 1, …]). The sampling frequency must be the original one, i.e. 1 value per 30 seconds if the staging was done in 30 seconds epochs. Using an upsampled hypnogram will result in an incorrect transition matrix. For best results, we recommend using an hypnogram cropped to either the time in bed (TIB) or the sleep period time (SPT).

Returns
countsarray

Counts transition matrix (number of transitions from stage X to stage Y).

probsarray

Conditional probability transition matrix, i.e. given that current state is X, what is the probability that the next state is Y. probs is a right stochastic matrix, i.e. each row sums to 1. See more details at: https://en.wikipedia.org/wiki/Stochastic_matrix

Examples

>>> from yasa import transition_matrix
>>> a = [1, 1, 1, 0, 0, 2, 2, 0, 2, 0, 1, 1, 0, 0]
>>> counts, probs = transition_matrix(a)
>>> counts
0  1  2
Stage
0      2  1  2
1      2  3  0
2      2  0  1

>>> probs
0    1         2
Stage
0      0.400000  0.2  0.400000
1      0.400000  0.6  0.000000
2      0.666667  0.0  0.333333