calibrate: shiftvector – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

shiftvector

Compute a shift vector for a calibrated axis.

Description

shiftvector computes two shift vectors perpendicular to the supplied biplot or scatterplot axis g. The vector norm is computed from the two most extreme data points.

Usage

shiftvector(g, X, x = c(1, 0), verbose = FALSE)

Arguments

`g`	a biplot or scatterplot axis
`X`	a n by 2 matrix of scatterplot or biplot coordinates
`x`	reference axis, (1,0) by default
`verbose`	print information or not

Details

shiftvector locates the tow most extreme datapoints in the direction perpendicular to axis g.

Value

`dr`	the right (w.r.t. the direction of `g`) shift vector
`dl`	the left (w.r.t. the direction of `g`) shift vector

Author(s)

Jan Graffelman (jan.graffelman@upc.edu)

References

Graffelman, J. and van Eeuwijk, F.A. (2005) Calibration of multivariate scatter plots for exploratory analysis of relations within and between sets of variables in genomic research Biometrical Journal, 47(6) pp. 863-879.

Graffelman, J. (2006) A guide to biplot calibration.

Examples

X <- matrix(rnorm(100),ncol=2)
Xs <- scale(X)

g <- c(1,1)

plot(Xs[,1],Xs[,2],asp=1,pch=19)
textxy(Xs[,1],Xs[,2],1:nrow(X))

arrows(0,0,g[1],g[2])
text(g[1],g[2],"g",pos=1)

out <- shiftvector(g,X,verbose=TRUE)
dr <- out$dr
dl <- out$dl

arrows(0,0,dl[1],dl[2])
text(dl[1],dl[2],"dl",pos=1)

arrows(0,0,dr[1],dr[2])
text(dr[1],dr[2],"dr",pos=1)

calibrate

Calibration of Scatterplot and Biplot Axes

v1.7.7

GPL-2

Authors

Jan Graffelman <jan.graffelman@upc.edu>

Initial release

2020-06-18