Function aggregate_attr

nodedb-array/src/query/aggregate.rs:134–144

Reduce one attr column over all rows of a tile. `attr_idx` must be in range; non-numeric / null cells are skipped (Count includes non-null cells regardless of dtype, since "count of cells with this attribute populated" is a sensible fold across all attr types).

(tile: &SparseTile, attr_idx: usize, reducer: Reducer)

/// non-null cells regardless of dtype, since "count of cells with this
/// attribute populated" is a sensible fold across all attr types).
pub fn aggregate_attr(tile: &SparseTile, attr_idx: usize, reducer: Reducer) -> AggregateResult {
    let Some(col) = tile.attr_cols.get(attr_idx) else {
        return empty(reducer);
    };
    let mut acc = empty(reducer);
    for v in col {
        let one = single_cell(v, reducer);
        acc = acc.merge(one);
    }
    acc
}

fn single_cell(v: &CellValue, reducer: Reducer) -> AggregateResult {
    use AggregateResult::*;