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")