preProcess

0th

Percentile

Pre-Processing of Predictors

Pre-processing transformation (centering, scaling etc) can be estimated from the training data and applied to any data set with the same variables.

Keywords
utilities
Usage
preProcess(x, ...)

## S3 method for class 'default': preProcess(x, method = c("center", "scale"), thresh = 0.95, na.remove = TRUE, ...)

## S3 method for class 'preProcess': predict(object, newdata, ...)

Arguments
x
a matrix or data frame
method
a character vector specifying the type of processing. Possible values are "center", "scale", "pca" and "spartialSign"
thresh
a cutoff for the cumulative percent of variance to be retained by PCA
na.remove
a logical; should missing values be removed from the calculations?
object
an object of class preProcess
newdata
a matrix or data frame of new data to be pre-processed
...
Additional arguments (currently this argument is not used)
Details

The operations are applied in this order: centering, scaling, PCA and spatial sign. If PCA is requested but scaling is not, the values will still be scaled.

The function will throw an error of any variables in x has less than two unique values.

Value

  • preProcess results in a list with elements
  • callthe function call
  • dimthe dimensions of x
  • meana vector of means (if centering was requested)
  • stda vector of standard deviations (if scaling or PCA was requested)
  • rotationa matrix of eigenvectors if PCA was requested
  • methodthe value ofmethod
  • threshthe value ofthresh
  • numCompthe number of principal components required of capture the specified amount of variance

References

Kuhn (2008), ``Building Predictive Models in R Using the caret'' (http://www.jstatsoft.org/v28/i05/)

See Also

prcomp, spatialSign

Aliases
  • preProcess
  • preProcess.default
  • predict.preProcess
Examples
data(BloodBrain)
# one variable has one unique value
preProc <- preProcess(bbbDescr[1:100,])

preProc <- preProcess(bbbDescr[1:100,-3])
training <- predict(preProc, bbbDescr[1:100,-3])
test <- predict(preProc, bbbDescr[101:208,-3])
Documentation reproduced from package caret, version 4.25, License: GPL-2

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