# Plot geographic regions defined as polygons

### Description

Produces plots of geographic regions defined by polygons, optionally filling the polygons with a color or grey shade dependent on a covariate.

### Usage

1 |

### Arguments

`pc` |
A named list of matrices. Each matrix has two columns. The matrix rows each define the
vertex of a boundary polygon. If a boundary is defined by several polygons, then each of these must be
separated by an |

`z` |
A vector of values associated with each area (item) of |

`scheme` |
One of |

`lab` |
label for plot. |

`...` |
other arguments to pass to plot (currently only if |

### Details

Any polygon within another polygon counts as a hole in the area. Further nesting is dealt with by
treating any point that is interior to an odd number of polygons as being within the area, and all other points
as being exterior. The routine is provided to facilitate plotting with models containing `mrf`

smooths.

### Value

Simply produces a plot.

### Author(s)

Simon Wood simon.wood@r-project.org

### See Also

`mrf`

and `columb.polys`

.

### Examples

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