# foldchange: Compute fold-change or convert between log-ratio and... In gtools: Various R Programming Tools

 foldchange 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)
```

gtools documentation built on July 12, 2022, 1:06 a.m.