Return points inside or outside a polygon.

`pip(pts,poly,out=FALSE,bound=NULL,quiet=TRUE)`

## Arguments

- pts
A points data set

- poly
A polygon data set

- out
If `out=TRUE`

, return the points outside the polygon, else the points inside.

- bound
If points fall exactly on polygon boundaries, the default NULL gives arbitrary assignments. If TRUE, then all points "on" boundaries are set as within the polygon, if FALSE, outside.

- quiet
Do not report which points are on boundary for non-NULL bound

## Value

`pip`

returns the points of `pts`

that lie inside (or outside with
`out=TRUE`

)
the polygon `poly`

. Compare this with `inpip`

, which returns
the indices of
the points in the polygon, and `inout`

which returns a logical vector
indicating whether points are inside or outside.

## Details

`pip`

calls `inout`

, then selects the appropriate sub-set of points.

## References

Rowlingson, B. and Diggle, P. 1993 Splancs: spatial point pattern analysis
code in S-Plus. Computers and Geosciences, 19, 627-655;
the original sources can be accessed at:
https://www.maths.lancs.ac.uk/~rowlings/Splancs/. See also Bivand, R. and
Gebhardt, A. 2000 Implementing functions for spatial statistical analysis
using the R language. Journal of Geographical Systems, 2, 307-317.