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
`base` | Exponential base for the log-ratio.
`foldchange` | vector/matrix of fold-change values

### 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 discontinuity 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.

### Functions

- `foldchange`: Compute fold-change.

- `logratio2foldchange`: Compute foldchange from log-ratio values.

- `foldchange2logratio`: Compute log-ratio from fold-change 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 3.9.2.2 Index]