R: Compute fold-change or convert between log-ratio and...

foldchange {gtools} | R Documentation

## Compute fold-change or convert between log-ratio and fold-change.

### Description

`foldchange` computes the fold change for two sets of values. `logratio2foldchange` converts values from log-ratios to fold changes. `foldchange2logratio` does the reverse.

### Usage

    foldchange(num,denom)
    logratio2foldchange(logratio, base=2)
    foldchange2logratio(foldchange, base=2)

### Arguments

`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.

### Details

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 discontinuty between -1 and 1, which can cause significant problems when performing data analysis. Consequently statisticians prefer to use log-ratios.

### Value

A vector or matrix of the same dimensions as the input containing the converted values.

### Author(s)

Gregory R. Warnes greg@warnes.net

### Examples

      a <- 1:21
      b <- 21:1

      f <- foldchange(a,b)

      cbind(a,b,f)

[Package gtools version 3.5.0 Index]