readTopDownFiles {topdownr} | R Documentation

## Read top-down files.

### Description

It creates an TopDownSet object and is its only constructor.

### Usage

    readTopDownFiles(path, pattern = ".*", type = c("a", "b", "c", "x", "y",
      "z"), modifications = c("Carbamidomethyl", "Acetyl", "Met-loss"),
      adducts = data.frame(), neutralLoss = MSnbase::defaultNeutralLoss(),
      sequenceOrder = c("original", "random", "inverse"), tolerance = 5e-06,
      redundantIonMatch = c("remove", "closest"),
      redundantFragmentMatch = c("remove", "closest"),
      dropNonInformativeColumns = TRUE, sampleColumns = c("Mz", "AgcTarget",
      "EtdReagentTarget", "EtdActivation", "CidActivation", "HcdActivation",
      "UvpdActivation"), verbose = interactive())

### Arguments

`path` | `character`, path to directory that contains the top-down files.
`pattern` | `character`, a filename pattern, the default `.*` means all files.
`type` | `character`, type of fragments, currently a-c and x-z are supported, see `MSnbase::calculateFragments()` for details.
`modifications` | `character`, unimod names of modifications that should be applied. Currenlty just Acetyl (Unimod:1 but just protein N-term), Carbamidomethyl (Unimod:4) and Met-loss (Unimod:765) are supported. Met-loss removes M (if followed by A, C, G, P, S, T, or V; (see also http://www.unimod.org/modifications_view.php?editid1=1, http://www.unimod.org/modifications_view.php?editid1=4, and http://www.unimod.org/modifications_view.php?editid1=765 for details)). Use `NULL` to disable all modifications.
`adducts` | `data.frame`, with 3 columns, namely: mass, name, to, see details section.
`neutralLoss` | `list`, neutral loss that should be applied, see `MSnbase::calculateFragments()` and `MSnbase::defaultNeutralLoss()` for details.
`sequenceOrder` | `character`, order of the sequence before fragment calculation and matching is done. `"original"` doesn't change anything. `"inverse"` reverse the sequence and `"random"` arranges the amino acid sequence at random.
`tolerance` | `double`, tolerance in ppm that is used to match the theoretical fragments with the observed ones.
`redundantIonMatch` | `character`, a mz could be matched to one, two or more fragments. If it is matched against more than one fragment the match could be `"remove"`d or the match to the `"closest"` fragment could be chosen.
`redundantFragmentMatch` | `character`, one or more mz could be matched to the same fragment, these matches could be `"remove"`d or the match to the `"closest"` mz is chosen.
`dropNonInformativeColumns` | logical, should columns with just one identical value across all runs be removed?
`sampleColumns` | `character`, column names of the `colData()` used to define a sample (technical replicate). This is used to add the `Sample` column (used for easier aggregation, etc.).
`verbose` | `logical`, verbose output?

### Details

`readTopDownFiles` reads and processes all top-down files, namely:

- `.fasta` (protein sequence)

- `.mzML` (spectra)

- `.experiments.csv` (method/fragmentation conditions)

- `.txt` (scan header information)

`adducts`: Thermo's Xtract allows some mistakes in deisotoping, mostly it allows `+/- C13-C12` and `+/- H+`. The `adducts` argument takes a `data.frame` with the `mass` to add, the `name` that should assign to these new fragments and an information `to` whom the modification should be applied, e.g. for `H+` on `z`, `data.frame(mass=1.008, name="zpH", to="z")`.

Please note: The `adducts` are added to the output of `MSnbase::calculateFragments()`. That has some limitations, e.g. neutral loss calculation could not be done in topdownr-package. If neutral loss should be applied on adducts you have to create additional rows, e.g.: `data.frame(mass=c(1.008, 1.008), name=c("cpH", "cpH_"), to=c("c", "c_"))`.

### Value

A `TopDownSet` object.

### See Also

`MSnbase::calculateFragments()`, `MSnbase::defaultNeutralLoss()`

### Examples

    if (require("topdownrdata")) {
        # add H+ to z and no neutral loss of water
        tds <- readTopDownFiles(
            topdownrdata::topDownDataPath("myoglobin"),
            ## Use an artifical pattern to load just the fasta
            ## file and files from m/z == 1211, ETD reagent
            ## target 1e6 and first replicate to keep runtime
            ## of the example short
            pattern=".*fasta.gz$|1211_.*1e6_1",
            adducts=data.frame(mass=1.008, name="zpH", to="z"),
            neutralLoss=MSnbase::defaultNeutralLoss(
                disableWaterLoss=c("Cterm", "D", "E", "S", "T")),
            tolerance=25e-6
       )
    }

[Package topdownr version 1.2.0 Index]