R: Compute a shift vector for a calibrated axis.

shiftvector {calibrate} | R Documentation

## 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.

### See Also

`calibrate`

### 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)

[Package calibrate version 1.7.2 Index]