shotGroups (version 0.3)

getMaxPairDist: Maximum pairwise distance for a set of points

Description

Calculates the maximum of pairwise distances between points given a set of coordinates.

Usage

getMaxPairDist(xy)

## S3 method for class 'data.frame':
getMaxPairDist(xy)

## S3 method for class 'default':
getMaxPairDist(xy)

Arguments

xy

either a numerical (n x p)-matrix with the coordinates of n points in p-dimensional space (1 row of coordinates per point), or a data frame with either the variables X, Y or Point.X, Point.Y.

Value

• A list with the following components
• d
  numerical value with the maximum pairwise distance between points.
• idx
  a vector with two entries giving the row indices of the points that are farthest apart.

Details

No coordinate transforms are done (unlike in groupLocation, groupShape, groupSpread), i.e., origin is not assumed to be in top-left corner, and points are not taken relative to point of aim.

Examples

# coordinates given by a suitable data frame
(maxPD <- getMaxPairDist(DFsavage))

# plot points and point pair with maximum distance
plot(Point.Y ~ Point.X, data=DFsavage, asp=1, pch=16)
x0 <- DFsavage$Point.X[maxPD$idx[1]]     # 1st point x
y0 <- DFsavage$Point.Y[maxPD$idx[1]]     # 1st point y
x1 <- DFsavage$Point.X[maxPD$idx[2]]     # 2nd point x
y1 <- DFsavage$Point.Y[maxPD$idx[2]]     # 2nd point y
segments(x0, y0, x1, y1, col="green3", lwd=2)

# coordinates given by a matrix
xy <- matrix(round(rnorm(20, 100, 15), 1), ncol=2)
getMaxPairDist(xy)