Function average 

pub fn average<T, D>(
    a: &Array<T, D>,
    weights: Option<&Array<T, D>>,
    axis: Option<usize>,
) -> FerrayResult<Array<T, IxDyn>>
where
    T: Element + Float + Send + Sync,
    D: Dimension,

Weighted average of array elements.

When weights is None, equivalent to mean. When Some(w), computes sum(a * w) / sum(w) along the given axis (or over all elements when axis=None). The weights array must have the same shape as a (the 1-D-along-axis broadcasting form supported by NumPy is intentionally omitted here — call broadcast yourself first if you need it).

Analogous to numpy.average.

Errors

• FerrayError::InvalidValue if the array is empty.
• FerrayError::ShapeMismatch if weights.shape() != a.shape().
• FerrayError::InvalidValue if the weight sum along an axis is zero.