caret (version 5.07-001)

BoxCoxTrans.default: Box-Cox Transformations

Description

This class can be used to estimate a Box-Cox transformation and apply it to existing and future data

Usage

BoxCoxTrans(y, ...)
## S3 method for class 'default':
BoxCoxTrans(y, x = rep(1, length(y)), 
            fudge = 0.2, numUnique = 3, na.rm = FALSE, ...)
## S3 method for class 'BoxCoxTrans':
predict(object, newdata, ...)

Value

• BoxCoxTrans returns a list of class BoxCoxTrans with elements
• lambda
  estimated transformation value
• fudge
  value of fudge
• n
  number of data points used to estimate lambda
• summary
  the results of summary(y)
• ratio
  max(y)/min(y)
• skewness
  sample skewness statistic
• predict.BoxCoxTrans returns a numeric vector of transformed values

Details

This function is basically a wrapper for the boxcox function in the MASS library. It can be used to estimate the transformation and apply it to new data.

If any(y <= 0)<="" code=""> or if length(unique(y)) < numUnique, lambda is not estimated and no transformation is applied.

References

Box, G. E. P. and Cox, D. R. (1964) An analysis of transformations (with discussion). Journal of the Royal Statistical Society B, 26, 211-252.

See Also

boxcox, preProcess

Examples

data(BloodBrain)

ratio <- exp(logBBB)
bc <- BoxCoxTrans(ratio)

bc

predict(bc, ratio[1:5])


ratio[5] <- NA
bc2 <- BoxCoxTrans(ratio, bbbDescr$tpsa, na.rm = TRUE)
bc2