FitAR (version 1.94)

glog: glog transformation

Description

The glog is a better behaved log transformation when some data values are zero or just near zero.

Usage

glog(x, a = 1, InverseQ = FALSE)

Arguments

x

numeric vector of data

a

additive constant, often 1

InverseQ

inverse glog

Value

transformated data

Details

Basic properties of the glog transformation are illustrated in the Mathematica notebook glog.nb and its pdf version glog.pdf which are available in the package directory doc.

References

W. Huber, A. von Heydebreck, H. Sultmann, A. Poustka, and M. Vingron. Variance stablization applied to microarray data calibration and to quantification of differential expression. Bioinformatics, 18: S96-S10 2002.

See Also

bxcx

Examples

#usual log transformation doesn't work
all(is.finite(log(sunspot.month)))
#either shifted log
all(is.finite(log(sunspot.month+1)))
#or glog works
all(is.finite(glog(sunspot.month)))
#but glog may be better, especially for values <1 but >=0