# Convert a data.frame of boundary points into a SpatialPolgonsDataFrame

Source:`R/bru.spatial.R`

`spoly.Rd`

A polygon can be described as a sequence of points defining the polygon's boundary.
When given such a sequence (anti clockwise!) this function creates a
SpatialPolygonsDataFrame holding the polygon decribed. By default, the
first two columns of `data`

are assumed to define the x and y coordinates
of the points. This behavior can ba changed using the `cols`

parameter, which
points out the names of the columns holding the coordinates. The coordinate
reference system of the resulting spatial polygon can be set via the `crs`

paraemter. Posterior conversion to a different CRS is supported using the
`to.crs`

parameter.

## Arguments

- data
A data.frame of points describing the boundary of the polygon

- cols
Column names of the x and y coordinates within the data

- crs
Coordinate reference system of the points

- to.crs
Coordinate reference system for the SpatialLines ouput.

## Examples

```
# \donttest{
# Create data frame of boundary points (anti clockwise!)
pts <- data.frame(
x = c(1, 2, 1.7, 1.3),
y = c(1, 1, 2, 2)
)
# Convert to SpatialPolygonsDataFrame
pol <- spoly(pts)
if (require(ggplot2, quietly = TRUE) &&
require(ggpolypath, quietly = TRUE)) {
# Plot it!
ggplot() +
gg(pol)
}
#> Regions defined for each Polygons
# }
```