`variance`

Calculates the variance.

Syntax


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variance(x, k)


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m = variance(x, k)

Calculates the variance of all the observations.

That is

σ^{2} = \frac{1}{n - 1} \sum_{i = 1}^{n} {(x_{i} - \bar{x})}^{2}

$x_i,i=1,2,\cdots,n$ $i$ -th observed value, and

\bar{x} = \frac{1}{n} \sum_{i}^{n} x_{i}

$\sigma$ is the unbiased estimate of the standard deviation.


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>>> from OpenHA.processing.feature import variance
>>> import numpy as np

>>> x = np.array([0, 1, 2, 3, 4])
>>> print(variance(x))

2.5

x —— A N-D array of observations.

For an n-by-m array, it indicates n observations with m features.

Name of the parameters	Is optional?	Source, dialog or input port?
`x`	No	Input port