is_point_inside {bivrp}

Determine if point is inside or outside a simple polygon area

Description

Returns whether a point is inside or outside the convex polygon formed with the coordinates in a data frame or matrix

Usage

is_point_inside(point, polyg)

Arguments

point

vector of two values for a point in the Cartesian plane

polyg

data frame or matrix with the coordinates forming the convex polygon

Details

The algorithm used here draws a ray from the point and counts the number of intersections made with the polygon. If the number of intersections is only one, then this means the point is inside the convex polygon.

Value

This function returns TRUE, if the point is inside and FALSE, otherwise.

Author(s)

Rafael A. Moral <[e-mail]> and John Hinde

Examples

my_polygon <- data.frame(c(1, 2, 3, 4, 3),
                         c(1, 0, .5, 3, 4))
points_to_test <- list(c(0, 0), c(2.5, 1), c(3.5, 4))

unlist(lapply(points_to_test, is_point_inside, my_polygon))