precSelection {MSnbase} | R Documentation

## Number of precursor selection events

### Description

`precSelection` computes the number of selection events each precursor ions has undergone in an tandem MS experiment. This will be a function of amount of peptide loaded, chromatography efficiency, exclusion time,... and is useful when optimising and experimental setup. This function returns a named integer vector or length equal to the number of unique precursor MZ values in the original experiment. See `n` parameter to set the number of MZ significant decimals.

`precSelectionTable` is a wrapper around `precSelection` and returns a table with the number of single, 2-fold, ... selection events.

### Usage

    precSelection(object,n)

### Arguments

`object` | An instane of class `"MSnExp"`.
`n` | The number of decimal places to round the precursor MZ to. Is passed to the round function.

### Value

A named integer in case of `precSelection` and a `table` for `precSelectionTable`.

### Author(s)

Laurent Gatto <lg390@cam.ac.uk>

### Examples

    precSelection(itraqdata)
    precSelection(itraqdata,n=2)
    precSelectionTable(itraqdata)
    ## only single selection event in this reduced exeriment

[Package MSnbase version 2.12.0 Index]