R: Scree Plots

screeplot {stats} R Documentation

Scree Plots

Description

screeplot.default plots the variances against the number of the principal component. This is also the plot method for classes "princomp" and "prcomp".

Usage

screeplot(x, ...)
## Default S3 method:
screeplot(x, npcs = min(10, length(x$sdev)),
 type = c("barplot", "lines"),
 main = deparse1(substitute(x)), ...)

Arguments

x

an object containing a sdev component, such as that returned by princomp() and prcomp().

npcs

the number of components to be plotted.

type

the type of plot. Can be abbreviated.

main, ...

graphics parameters.

References

Mardia, K. V., J. T. Kent and J. M. Bibby (1979). Multivariate Analysis, London: Academic Press.

Venables, W. N. and B. D. Ripley (2002). Modern Applied Statistics with S, Springer-Verlag.

Examples

require(graphics)
## The variances of the variables in the
## USArrests data vary by orders of magnitude, so scaling is appropriate
(pc.cr <- princomp(USArrests, cor = TRUE)) # inappropriate
screeplot(pc.cr)
fit <- princomp(covmat = Harman74.cor)
screeplot(fit)
screeplot(fit, npcs = 24, type = "lines")