pub fn weighted_average_position(rows: &[PositionRow]) -> Result<f64, SerpError>Expand description
Impression-weighted average position across many rows.
This is the only correct way to combine per-query or per-page average positions: a plain mean of the position column lets a row with three impressions outvote a row with thirty thousand.
ยงErrors
Returns SerpError::EmptyInput for an empty slice, SerpError::InvalidPosition
for a non-finite or sub-1.0 position, and SerpError::NoImpressions when every row
has zero impressions.