weighted_variance

sofia_redux.toolkit.resampling.weighted_variance(error, weights, weightsum=None)

Utility function to calculate the biased weighted variance.

Calculates the biased weighted variance from data errors as:

\[V = \frac{\sum{(w\sigma)^2}}{(\sum{w})^2}\]

Parameters:

errornumpy.ndarray (ndata,)

1-sigma error values.

weightsnumpy.ndarray (ndata,)

Data weights.

weightsumint or float, optional

Sum of weights. Optionally passed in for speed if pre-calculated.

Returns:

weighted_variancefloat

The weighted variance.