createSTDdbGC {metaMS} | R Documentation

## Create an in-house database for GC-MS annotation

### Description

For creating an in-house instrument-specific annotation database, injections of pure standards need to be processed. All patterns in the vicinity of the retention time of the standard (to be provided by the user) will be compared to an external database - in case of a sufficient match, they will be retained in the database. The `generateStdDBGC` is not meant to be called directly by the user.

### Usage

    createSTDdbGC(stdInfo, settings, extDB = NULL, manualDB = NULL,
                  RIstandards = NULL, nSlaves = 0)
    generateStdDBGC(totalXset, settings, extDB = NULL, manualDB = NULL,
                    RIstandards = NULL)

### Arguments

`stdInfo` | Information of the standards, given in the form of a `data.frame`. Minimal information: `stdFile`, `Name`, `CAS`, monoisotopic mass (`monoMW`), and retention time (`rt`). The filenames in slot `stdFile` should include path information. If this argument is NULL, this function can be used to process a manually curated DB. Arguments `stdInfo` and `manualDB` cannot be both NULL.
`settings` | A list of settings, to be used in peak picking and pattern comparison.
`extDB` | The external database containing spectra, with which to compare the patterns found in the standards files.
`manualDB` | A database of manually curated spectra, that will be incorporated in the final DB without any further checks.
`totalXset` | A list of xset objects, as generated by `peakDetection`.
`RIstandards` | A two-column matrix containing for the standards defining the RI scale both retention times and retention indices. If not given, no RI values will be calculated and retention times will be used instead.
`nSlaves` | Number of cores to be used in peak picking.

### Details

Function `createSTDdbGC` creates a database object containing validated pseudospectra for a number of compounds. The injections of the standards, described in the input object `stdInfo`, are processed using function `processStandards`; comparison with the external database, inclusion of manual compounds and final formatting are done in function `generateStdDBGC`. Several situations can be envisaged:

A: a series of injections of standards needs to be compared with a standard library, such as the NIST. In this case, both `stdInfo` and `extDB` need to be non-null, and the result will be a database in which the entries have a sufficient match with the external DB. If `manualDB` is also non-null, these entries will be added too (without checking).

B: for a series of injections no standard library information is available (`extDB` is NULL, and `stdInfo` is not), and the function simply returns all patterns eluting around the indicated retention time. This allows for subsequent manual validation and pruning. If `manualDB` is non-null, these entries will be added, but since this is a somewhat unusual thing to do, a warning will be given.

C: a manual database needs to be processed to be useable as a real database. This basically entails renaming the `rt` and `rt.sd` fields into `std.rt` and `std.rt.sd`, and a similar action for any `RI` field.

### Value

The output of `createSTDdbGC` (and `generateStdDBGC`, which is the last function called in `createSTDdbGC`) is a list, where every entry describes one compound/spectrum combination. For use in annotation, the following fields are mandatory: `Name`, `std.rt`, `pspectrum` and `monoMW`.

### Author(s)

Ron Wehrens

### See Also

`processStandards`, `generateStdDBGC`

### Examples

      data(threeStdsNIST)  ## provides object smallDB, excerpt from NIST DB
      ## Not run:
    if (require(metaMSdata)) {
      ## Sitation A: create a DB of standards.
      ## first tell the system where to look
      data(threeStdsInfo)
      all.files <- list.files(system.file("extdata", package = "metaMSdata"),
                              pattern = "_GC_", full.names = TRUE)
      stdInfo[,"stdFile"] <- rep(all.files[3], 3)

      data(FEMsettings)    ## provides a.o. TSQXLS.GC, the GC settings file
      data(threeStdsNIST)  ## provides object smallDB, excerpt from NIST DB

      DB <- createSTDdbGC(stdInfo, TSQXLS.GC, extDB = smallDB)
      }
      ## saved in "threeStdsDB.RData" in the data directory of the metaMS
      ## package

      ## Situation B: do not check the data with an external database. Now
      ## the fields bestDBmatch and validation will be absent.
      DB <- createSTDdbGC(stdInfo, TSQXLS.GC, extDB = NULL)

      ## Situation C: create a DB directly from an msp file (manual DB)
      manual.fname <- list.files(system.file("extdata", package = "metaMSdata"),
                                 pattern = "msp", full.names = TRUE)
      manual <- read.msp(manual.fname)
      DB <- createSTDdbGC(stdInfo = NULL, settings = TSQXLS.GC,
                          manualDB = manual)

    ## End(Not run)

[Package metaMS version 1.28.0 Index]