plot-methods {MSnbase} | R Documentation

## Plotting 'MSnExp' and 'Spectrum' object(s)

### Description

These methods provide the functionality to plot mass spectrometry data provided as `MSnExp`, `OnDiskMSnExp` or `Spectrum` objects. Most functions plot mass spectra M/Z values against intensities.

Full spectra (using the `full` parameter) or specific peaks of interest can be plotted using the `reporters` parameter. If `reporters` are specified and `full` is set to 'TRUE', a sub-figure of the reporter ions is inlaid inside the full spectrum.

If an `"MSnExp"` is provided as argument, all the spectra are aligned vertically. Experiments can be subset to extract spectra of interest using the `[` operator or `extractPrecSpectra` methods.

Most methods make use the `ggplot2` system in which case an object of class 'ggplot' is returned invisibly.

If a single `"Spectrum2"` and a `"character"` representing a valid peptide sequence are passed as argument, the expected fragement ions are calculated and matched/annotated on the spectum plot.

### Arguments

`x` | Objects of class `"Spectrum"`, `"Spectrum2"` or `"MSnExp"` to be plotted.
`y` | Missing, `"Spectrum"` or `"character"`.
`reporters` | An object of class `"ReporterIons"` that defines the peaks to be plotted. If not specified, `full` must be set to 'TRUE'.
`full` | Logical indicating whether full spectrum (respectively spectra) of only reporter ions of interest should be plotted. Default is 'FALSE', in which case `reporters` must be defined.
`centroided.` | Logical indicating if spectrum or spectra are in centroided mode, in which case peaks are plotted as histograms, rather than curves.
`plot` | Logical specifying whether plot should be printed to current device. Default is 'TRUE'.
`w1` | Width of sticks for full centroided spectra. Default is to use maximum MZ value divided by 500.
`w2` | Width of histogram bars for centroided reporter ions plots. Default is 0.01.

See below for more details.

### Methods

`plot(signature(x = "MSnExp", y = "missing"), type = c("spectra", "XIC"), reporters = "ReporterIons", full = "logical", plot = "logical", ...)`

  For `type = "spectra"`: Plots all the spectra in the `MSnExp` object vertically. One of `reporters` must be defined or `full` set to 'TRUE'. In case of `MSnExp` objects, repoter ions are not inlaid when `full` is 'TRUE'.

  For `type = "XIC"`: Plots a combined plot of retention time against m/z values and retention time against largest signal per spectrum for each file. Data points are colored by intensity. The lower part of the plot represents the location of the individual signals in the retention time - m/z space, the upper part the base peak chromatogram of the data (i.e. the largest signal for each spectrum). This plot type is restricted to MS level 1 data and is most useful for LC-MS data. Ideally, the `MSnExp` (or `OnDiskMSnExp`) object should be filtered first using the `filterRt` and `filterMz` functions to narrow on an ion of interest. See examples below. This plot uses base R plotting. Additional arguments to the `plot` function can be passed with `...`.

  Additional arguments for `type = "XIC"` are:

  `col`

    color for the border of the points. Defaults to `col = "grey"`.

  `colramp`

    color function/ramp to be used for the intensity-dependent background color of data points. Defaults to `colramp = topo.colors`.

  `grid.color`

    color for the grid lines. Defaults to `grid.color = "lightgrey"`; use `grid.color = NA` to disable grid lines altogether.

  `pch`

    point character. Defaults to `pch = 21`

  .

  `...`

    additional parameters for the low-level `plot` function.

`plot(signature(x = "Spectrum", y = "missing"), reporters = "ReporterIons", full = "logical", centroided. = "logical", plot = "logical", w1, w2)`

  Displays the MZs against intensities of the `Spectrum` object as a line plot. At least one of `reporters` being defined or `full` set to 'TRUE' is required. `reporters` and `full` are used only for `"Spectrum2"` objects. Full `"Spectrum1"` spectra are plotted by default.

`plot(signature(x = "Spectrum2", y = "character"), orientation = "numeric", add = "logical", col = "character", pch, xlab = "character", ylab = "character", xlim = "numeric", ylim = "numeric", tolerance = "numeric", relative = "logical", type = "character", modifications = "numeric", x = "numeric", fragments = "data.frame", fragments.cex = "numeric", ... )`

  Plots a single MS2 spectrum and annotates the fragment ions based on the matching between the peaks in `x` and the fragment peaks calculated from the peptide sequence `y`. The default values are `orientation=1`, `add=FALSE`, `col="#74ADD1"`, `pch=NA`, `xlab="m/z"`, `ylab="intensity"`, `ylim=c(0, 1)`, `tolerance=25e-6`, relative=TRUE, type=c("b", "y"), `modifications=c(C=160.030649)`, `z=1`, fragments=`MSnbase:::calculateFragments_Spectrum2` and `fragments.cex=0.75`. Additional arguments `...` are passed to `plot.default`.

### Author(s)

Laurent Gatto <lg390@cam.ac.uk>, Johannes Rainer and Sebastian Gibb

### See Also

`calculateFragments` to calculate ions produced by fragmentation and `plot.Spectrum.Spectrum` to plot and compare 2 spectra and their shared peaks.

`Chromatogram` for plotting of chromatographic data.

### Examples

    data(itraqdata)
    ## plotting experiments
    plot(itraqdata[1:2], reporters = iTRAQ4)
    plot(itraqdata[1:2], full = TRUE)
    ## plotting spectra
    plot(itraqdata[[1]],reporters = iTRAQ4, full = TRUE)

    itraqdata2 <- pickPeaks(itraqdata)
    i <- 14
    s <- as.character(fData(itraqdata2)[i, "PeptideSequence"])
    plot(itraqdata2[[i]], s, main = s)

    ## Load profile-mode LC-MS files
    library(msdata)
    od <- readMSData(dir(system.file("sciex", package = "msdata"),
                         full.names = TRUE), mode = "onDisk")
    ## Restrict the MS data to signal for serine
    serine <- filterMz(filterRt(od, rt = c(175, 190)), mz = c(106.04, 106.06))
    plot(serine, type = "XIC")

    ## Same plot but using heat.colors, rectangles and no point border
    plot(serine, type = "XIC", pch = 22, colramp = heat.colors, col = NA)

[Package MSnbase version 2.15.7 Index]