R: Screeplots

screeplot {stats} | R Documentation

## Screeplots

### 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

    ## 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.

### See Also

`princomp` and `prcomp`.

### 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")

[Package stats version 4.0.5 Index]