distancePointToLine: Finds the minimum distance(s) between point(s) and a line

Description

Finds the minimum distance between a point and a line or multiple points and a line in two or three dimensions.

Usage

distancePointToLine(p, l1, l2 = NULL)

Arguments

a vector of a single point or a matrix of multiple points

a vector describing a point on a line or a list with line constants

if l1 is a point, a second point on a line

Value

a vector of distance(s)

Details

If p is a vector, the function returns the distance between a point and the line input. If p is a matrix, the function returns the distance between each point in the matrix (defined by each row) and the line input. If p is a vector, the length must be 2 or 3 (2D or 3D, respectively). If p is a matrix, the number of columns must be 2 or 3 (2D or 3D, respectively).

The line input can be defined using one of three standard ways: two points on the line, 'm' and 'b' constants and direction numbers (a vector parallel to the line). If l1 is a vector, this is taken as one point on the line and l2 must be a second point on the line. If l1 is a list, the named objects must correspond to one of these three line definitions. Two points on the line are defined as l1$l1 and l1$l2. 'm' and 'b' are defined as l1$m and l1$b. And the direction numbers 'abc' are defined as l1$a, l1$b and l1$c.

Examples

Run this code

# NOT RUN {
## FIND THE DISTANCE BETWEEN A 2D POINT AND A LINE DEFINED BY A SLOPE AND Y-INTERCEPT
distancePointToLine(p=c(0, 2), l1=list(m=0, b=1))

## FIND THE DISTANCE BETWEEN A 2D POINT AND A LINE DEFINED BY TWO POINTS ON THE LINE
distancePointToLine(p=c(0, 5), l1=list(l1=c(2, 4), l2=c(2, 1)))

## FIND THE DISTANCE BETWEEN MULTIPLE 2D POINTS AND A LINE DEFINED BY A SLOPE AND Y-INTERCEPT
p <- matrix(c(0, 0, 1, 1, 2, 2), nrow=3, ncol=2, byrow=TRUE)
distancePointToLine(p=p, l1=list(m=0, b=1))

## FIND THE DISTANCE BETWEEN MULTIPLE 2D POINTS AND A LINE DEFINED BY DIRECTION NUMBERS
p <- matrix(c(0, -1.5, 1, -2, 2, 2), nrow=3, ncol=2, byrow=TRUE)
distancePointToLine(p=p, l1=list(a=1, b=2, c=3))

## FIND THE DISTANCE BETWEEN A 3D POINT AND A LINE DEFINED BY TWO POINTS ON THE LINE
## HERE THE DISTANCE IS EQUAL TO sqrt(2)
distancePointToLine(p=c(1, 1, 1), l1=c(0, 0, 0), l2=c(1, 0, 0))

## FIND THE DISTANCE BETWEEN MULTIPLE 3D POINTS AND A LINE DEFINED BY TWO POINTS ON THE LINE
p <- matrix(c(0, 0, 0, 1, 1, 1, 2, 2, 2), nrow=3, ncol=3, byrow=TRUE)
distancePointToLine(p=p, l1=list(l1=c(0, 0, 0), l2=c(1, 0, 0)))
# }