R: Counter Clockwise check

CCcheck {GEOmap} | R Documentation

## Counter Clockwise check

### Description

Check for counter-clockwise orientation for polygons. Positive is counterclockwise.

### Usage

    CCcheck(Z)

### Arguments

`Z` | list(x,y)

### Details

Uses sign of the area of the polygon to determine polarity.

### Value

`j` | sign of area

### Note

Based on the idea calculated area of a polygon.

### Author(s)

Jonathan M. Lees<jonathan.lees@unc.edu>

### Examples

    Y=list()
    Y$x=c(170,175,184,191,194,190,177,166,162,164)
    Y$y=c(-54,-60,-60,-50,-26,8,34,37,10,-15)

    plot(c(160, 200),c(-85, 85), type='n')
    points(Y)
    lines(Y)

    CCcheck(Y)

    Z = list(x=rev(Y$x), y=rev(Y$y))

    CCcheck(Z)

[Package GEOmap version 2.4-0 Index]