Marc in the box - 4 months ago 37

R Question

Does anyone know how to calculate the area in common between 2 or more polygons in R? I would like to have the output of such a calculation be the coordinates of a new polygon for that area of overlap.

Cheers

Answer

EDIT: these days I would use the 'intersect', 'cover', 'erase', 'union' and related functions in the 'raster' package. They do the hard work to keep the top-level object and attributes.

ORIG:
You could use the `rgeos`

package with its `gIntersection`

function. Successive calls between pairs and resulting intersections will get you there. See

```
library(rgeos)
?gIntersection
```

You will need to get into the structure of "SpatialPolygons" in the `sp`

package to get the final coordinates. See the vignette("sp").