glog transformation
The glog is a better behaved log transformation when some data values are zero or just near zero.
glog(x, a = 1, InverseQ = FALSE)
x |
numeric vector of data |
a |
additive constant, often 1 |
InverseQ |
inverse glog |
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.
transformated data
A.I. McLeod
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.
#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
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