featureCV {MSnbase} | R Documentation

## Calculates coeffivient of variation for features

### Description

This function calculates the column-wise coefficient of variation (CV), i.e. the ration between the standard deviation and the mean, for the features in an `"MSnSet"`. The CVs are calculated for the groups of features defined by `groupBy`. For groups defined by single features, `NA` is returned.

### Usage

    featureCV(x, groupBy, na.rm = TRUE, norm = c("sum", "max", "none",
      "center.mean", "center.median", "quantiles", "quantiles.robust"))

### Arguments

`x` | An instance of class `"MSnSet"`.
`groupBy` | An object of class `factor` defining how to summerise the features.
`na.rm` | A `logical` defining whether missing values should be removed.
`norm` | One of 'none' (default), 'sum', 'max', 'center.mean', 'center.median' 'quantiles' or 'quantiles.robust' defining if and how the data should be normalised prior to CV calculation. See `normalise` for more details.

### Value

A `matrix` of dimensions `length(levels(groupBy))` by `ncol(x)` with the respecive CVs.

### Author(s)

Laurent Gatto <lg390@cam.ac.uk>, Sebastian Gibb <mail@sebastiangibb.de>

### See Also

`combineFeatures`

### Examples

    data(msnset)
    msnset <- msnset[1:4]
    gb <- factor(rep(1:2, each = 2))
    featureCV(msnset, gb)

[Package MSnbase version 2.4.2 Index]