Function regular_grid_through 

pub fn regular_grid_through(
    x: &CoordArray,
    y: &CoordArray,
    f: impl Fn(f64, f64) -> Option<(f64, f64)>,
    through: &str,
    tolerance: Tolerance,
) -> (Option<Affine>, Report)

Test whether 2D coordinate arrays (centres, shaped [nrow, ncol]) form an affine grid after mapping each (x, y) pair through f. through names the frame f maps into. None from f fails the test.

On success returns the affine transform in the through frame, for index order [row, col] as Positions::Affine expects.