Compute fold-change or convert between log-ratio and fold-change.
foldchange computes the fold change for two sets of values.
logratio2foldchange converts values from log-ratios to fold
changes. foldchange2logratio does the reverse.
foldchange(num,denom) logratio2foldchange(logratio, base=2) foldchange2logratio(foldchange, base=2)
num,denom |
vector/matrix of numeric values |
logratio |
vector/matrix of log-ratio values |
foldchange |
vector/matrix of fold-change values |
base |
Exponential base for the log-ratio. |
Fold changes are commonly used in the biological sciences as a mechanism for comparing the relative size of two measurements. They are computed as: num/denom if num>denom, and as -denom/num otherwise.
Fold-changes have the advantage of ease of interpretation and symmetry about num=denom, but suffer from a discontinuity between -1 and 1, which can cause significant problems when performing data analysis. Consequently statisticians prefer to use log-ratios.
A vector or matrix of the same dimensions as the input containing the converted values.
Gregory R. Warnes greg@warnes.net
a <- 1:21 b <- 21:1 f <- foldchange(a,b) cbind(a,b,f)
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.