# biplot.princomp

##### Biplot for Principal Components

Produces a biplot (in the strict sense) from the output of
`princomp`

or `prcomp`

- Keywords
- multivariate, hplot

##### Usage

```
## S3 method for class 'prcomp':
biplot(x, choices = 1:2, scale = 1, pc.biplot = FALSE, \dots)
```## S3 method for class 'princomp':
biplot(x, choices = 1:2, scale = 1, pc.biplot = FALSE, \dots)

##### Arguments

- x
- an object of class
`"princomp"`

. - choices
- length 2 vector specifying the components to plot. Only the default is a biplot in the strict sense.
- scale
- The variables are scaled by
`lambda ^ scale`

and the observations are scaled by`lambda ^ (1-scale)`

where`lambda`

are the singular values as computed by`princomp`

. Normally`0 <= scale="" <="1, and a warning will be issued if the specified`

`scale`

is outside this range. - pc.biplot
- If true, use what Gabriel (1971) refers to as a "principal component
biplot", with
`lambda = 1`

and observations scaled up by sqrt(n) and variables scaled down by sqrt(n). Then inner products between variables approximate covariances and distances between observations approximate Mahalanobis distance. - ...
- optional arguments to be passed to
`biplot.default`

.

##### Details

This is a method for the generic function `biplot`

. There is
considerable confusion over the precise definitions: those of the
original paper, Gabriel (1971), are followed here. Gabriel and
Odoroff (1990) use the same definitions, but their plots actually
correspond to `pc.biplot = TRUE`

.

##### Side Effects

a plot is produced on the current graphics device.

##### References

Gabriel, K. R. (1971).
The biplot graphical display of matrices with applications to
principal component analysis.
*Biometrika*, **58**, 453--467.

Gabriel, K. R. and Odoroff, C. L. (1990).
Biplots in biomedical research.
*Statistics in Medicine*, **9**, 469--485.

##### See Also

##### Examples

`library(stats)`

```
require(graphics)
biplot(princomp(USArrests))
```

*Documentation reproduced from package stats, version 3.3, License: Part of R 3.3*