extractPrecSpectra-methods: Extracts precursor-specific spectra from an 'MSnExp' object

In MSnbase: Base Functions and Classes for Mass Spectrometry and Proteomics

Description

Extracts the MSMS spectra that originate from the precursor(s) having the same MZ value as defined in theprec argument.

A warning will be issued of one or several of the precursor MZ values in prec are absent in the experiment precursor MZ values (i.e in precursorMz(object)).

Methods

signature(object = "MSnExp", prec = "numeric")

Returns an "MSnExp" containing MSMS spectra whose precursor MZ values are in prec.

Author(s)

Laurent Gatto <[e-mail]>

Examples

file <- dir(system.file(package="MSnbase",dir="extdata"),
            full.name=TRUE,pattern="mzXML$")
aa <- readMSData(file,verbose=FALSE)
my.prec <- precursorMz(aa)[1]
my.prec
bb <- extractPrecSpectra(aa,my.prec)
precursorMz(bb)
processingData(bb)

Example output

Loading required package: BiocGenerics
Loading required package: parallel

Attaching package: ‘BiocGenerics’

The following objects are masked from ‘package:parallel’:

    clusterApply, clusterApplyLB, clusterCall, clusterEvalQ,
    clusterExport, clusterMap, parApply, parCapply, parLapply,
    parLapplyLB, parRapply, parSapply, parSapplyLB

The following objects are masked from ‘package:stats’:

    IQR, mad, sd, var, xtabs

The following objects are masked from ‘package:base’:

    anyDuplicated, append, as.data.frame, basename, cbind, colnames,
    dirname, do.call, duplicated, eval, evalq, Filter, Find, get, grep,
    grepl, intersect, is.unsorted, lapply, Map, mapply, match, mget,
    order, paste, pmax, pmax.int, pmin, pmin.int, Position, rank,
    rbind, Reduce, rownames, sapply, setdiff, sort, table, tapply,
    union, unique, unsplit, which.max, which.min

Loading required package: Biobase
Welcome to Bioconductor

    Vignettes contain introductory material; view with
    'browseVignettes()'. To cite Bioconductor, see
    'citation("Biobase")', and for packages 'citation("pkgname")'.

Loading required package: mzR
Loading required package: Rcpp
Loading required package: S4Vectors
Loading required package: stats4

Attaching package: ‘S4Vectors’

The following object is masked from ‘package:base’:

    expand.grid

Loading required package: ProtGenerics

Attaching package: ‘ProtGenerics’

The following object is masked from ‘package:stats’:

    smooth


This is MSnbase version 2.16.0 
  Visit https://lgatto.github.io/MSnbase/ to get started.


Attaching package: ‘MSnbase’

The following object is masked from ‘package:base’:

    trimws

   F1.S1 
645.3741 
   F1.S1    F1.S3 
645.3741 645.3741 
- - - Processing information - - -
Data loaded: Wed Jan 13 00:22:28 2021 
1 (2) precursors (spectra) extracted: Wed Jan 13 00:22:28 2021 
 MSnbase version: 2.16.0 

MSnbase documentation built on Jan. 23, 2021, 2 a.m.