yt.data_objects.derived_quantities.WeightedVariance

class yt.data_objects.derived_quantities.WeightedVariance(data_source)[source]

Calculates the weighted variance and weighted mean for a field or list of fields.

Where f is the field, w is the weight, and <f_w> is the weighted mean, the weighted variance is Sum_i( (f_i - <f_w>)^2 * w_i ) / Sum_i(w_i).

Parameters:

fields : field or list of fields

The field or fields of which the variance and mean values are to be calculated.

weight : field

The weight field.

Examples

>>> ds = load("IsolatedGalaxy/galaxy0030/galaxy0030")
>>> ad = ds.all_data()
>>> print ad.quantities.weighted_variance([("gas", "density"),
...                                        ("gas", "temperature")],
...                                       ("gas", "cell_mass"))

Attributes

Methods