ChemoSpec (version 1.60-4)

plot2Loadings: Plot PCA Loadings from a Spectra object Against Each Other

Description

Plots two PCA loadings specified by the user, and labels selected (extreme) points. Typically used to determine which variables (frequencies) are co-varying, although in spectroscopy most peaks are represented by several variables and hence there is a lot of co-varying going on. Also useful to determine which variables are contributing the most to the clustering on a score plot.

Usage

plot2Loadings(spectra, pca, title = "no title provided",
	loads = c(1, 2), tol = 0.05, ...)

Value

None. Side effect is a plot.

Rdversion

1.1

References

http://academic.depauw.edu/~hanson/ChemoSpec/ChemoSpec.html

See Also

See plotLoadings to plot one loading against the original variable (frequency) axis.

Examples

data(SrE.IR)
results <- classPCA(SrE.IR, choice = "noscale")
plot2Loadings(SrE.IR, title = "Serenoa repens IR Spectra", results,
	loads = c(1,2), tol = 0.05)