N-aray

N-aray transformers

Transformations done on sets of geometries:
- union - any set of geometries can be combined into a multi-type geometry when they have equal dimensions, or a geometry collection. It’s recommended to use union to combining.
- intersection and difference operate sequentially on all geometries. Example of intersection:

## Geometry set for 7 features 
## Geometry type: POLYGON
## Dimension:     XY
## Bounding box:  xmin: -1 ymin: -1.5 xmax: 2.7 ymax: 2
## CRS:           NA
## First 5 geometries:

## POLYGON ((-1 1, -0.5 1, -0.5 0, 0.7 0, 0.7 -1, ...

## POLYGON ((0.7 -1, 0.7 0, 1 0, 1 -1, 0.7 -1))

## POLYGON ((2.7 -1.5, 0.7 -1.5, 0.7 -1, 1 -1, 1 0...

## POLYGON ((1 0.5, 1.5 0.5, 1.5 0, 1 0, 1 0.5))

## POLYGON ((0.7 0.5, 1 0.5, 1 0, 0.7 0, 0.7 0.5))

Left: three overlapping squares -- how do we identify the small box where all three overlap? Right: unique, non-overlapping n-ary intersections

Figure 3.2: Left: three overlapping squares – how do we identify the small box where all three overlap? Right: unique, non-overlapping n-ary intersections