Navigate an MSnExp object by moving to the next or previous
spectrum.
navMS(i, object, msLevel, nav = c("nextMS", "prevMS"), ...)
nextMS(...)
prevMS(...)The name or index of the current spectrum
The MSnExp object
The MS level of the next or previous spectrum. If missing (default), then the level of the current spectrum is used.
One of "nextMS" or "prevMS", to obtain
the next or previous spectrum of level msLevel.
Additional parameters. Currently ignored.
An object of class Spectrum1 or Spectrum2,
depending on the value of msLevel or NULL, of no
spectrum is found.
f <- msdata::proteomics(full.names = TRUE, pattern = "MS3")
x <- readMSData(f, centroided. = c(FALSE, TRUE, FALSE), mode = "onDisk")
#> Warning: Reading different file formats in.
#> This is untested and you are welcome to try it out.
#> Please report back!
(sp <- which(msLevel(x) == 3)[2]) ## 2nd MS3 spectrum
#> F1.S009
#> 9
x[[sp]] ## curent MS3
#> Object of class "Spectrum2"
#> Precursor: 756.4332
#> Retention time: 73:43
#> Charge: 1
#> MSn level: 3
#> Peaks count: 1422
#> Total ion count: 972514
MSnbase:::nextMS(sp, x) ## next MS3
#> Object of class "Spectrum2"
#> Precursor: 466.1647
#> Retention time: 73:44
#> Charge: 0
#> MSn level: 3
#> Peaks count: 2281
#> Total ion count: 3908748
MSnbase:::prevMS(sp, x) ## prev MS3
#> Object of class "Spectrum2"
#> Precursor: 490.2629
#> Retention time: 73:43
#> Charge: 0
#> MSn level: 3
#> Peaks count: 2540
#> Total ion count: 9311294
MSnbase:::prevMS(sp, x, 2L) ## prev MS2
#> Object of class "Spectrum2"
#> Precursor: 675.6938
#> Retention time: 73:43
#> Charge: 3
#> MSn level: 2
#> Peaks count: 858
#> Total ion count: 627600.3
MSnbase:::prevMS(sp, x, 1L) ## prev MS1
#> Object of class "Spectrum1"
#> Retention time: 73:43
#> MSn level: 1
#> Total ion count: 48304
#> Polarity: 1