Scale vectors to fill the current plot

Calculates a scale factor so that a collection of vectors nearly fills the current plot, that is, the longest vector does not extend beyond the plot region.

Usage

vecscale(
  vectors,
  bbox = matrix(par("usr"), 2, 2),
  origin = c(0, 0),
  factor = 0.95
)

Arguments

vectors: a two-column matrix giving the end points of a collection of vectors
bbox: the bounding box of the containing plot region within which the vectors are to be plotted
origin: origin of the vectors
factor: maximum length of the rescaled vectors relative to the maximum possible

Value

scale factor, the multiplier of the vectors

Author

Michael Friendly

Examples


bbox <- matrix(c(-3, 3, -2, 2), 2, 2)
colnames(bbox) <- c("x","y")
rownames(bbox) <- c("min", "max")
bbox
#>      x  y
#> min -3 -2
#> max  3  2

vecs <- matrix( runif(10, -1, 1), 5, 2)

plot(bbox)
arrows(0, 0, vecs[,1], vecs[,2], angle=10, col="red")
(s <- vecscale(vecs))
#> [1] 2.310403
arrows(0, 0, s*vecs[,1], s*vecs[,2], angle=10)