This function unstacks a
Spectra2D object and conducts IRLBA
PCA on it.
To unstack, each F1 slice (parallel to F2) is concatenated one after the other
so that each 2D spectrum becomes a 1D spectrum. The length of this spectrum will be
equal to the length of the F2 dimension times the length of the F1 dimension.
PCA is performed on the collection of 1D spectra (one spectrum from each 2D spectrum).
The IRLBA algorithm is used because the resulting matrix (n samples in rows x F1 * F2 columns)
can be very large, and other PCA algorithms can struggle.
An object of S3 class
Integer. The number of components desired.
A character string indicating the choice of scaling. One of
Other parameters to be passed to
The scale choice
autoscale scales the columns by their standard
Pareto scales by the square root of the standard
"autoscale" is called "standard normal variate" or "correlation matrix PCA"
in some literature. This action is performed on the unstacked matrix, as is centering.
An object of classes
modified to include a list element called
$method, a character string describing the
pre-processing carried out and the type of PCA performed (used to annotate
Bryan A. Hanson, DePauw University.
J. Baglama and L. Reichel, "Augmented Implicitly Restarted Lanczos Bidiagonalization Methods" SIAM J. Sci. Comput. (2005).
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