readPlateList {cellHTS2} | R Documentation

## Read a collection of plate reader data files

### Description

Reads a collection of plate reader data files into a `cellHTS` object. The names of the files, plus additional information (plate number, repeat number, assay/treatment/condition) is expected to be stored in a tab-delimited table specified by the argument `filename`. Alternatively, the data can be provided directly from non file-based sources, e.g. a data base (see details).

### Usage

    readPlateList(filename, path=NA, name="anonymous", importFun,
    dec=".", verbose=interactive(), ...)

### Arguments

`filename` | the name of the plate list file (see details). This argument is just passed on to the `read.table` function, so any of the valid argument types for the `file` argument of `read.table` are valid here, too. Alternatively, a user-defined function which is supposed to create a table-like R object of the plate list. Additional arguments to `readPlateList` in ... will be passed on to this function.
`path` | a character of length 1 indicating the path in which to find the plate reader files. If the `importFun` argument is supplied, the value of `path` will not be automatically prepended to the file names. This has to be explicitely dealt with in the `importFun` function. See details.
`name` | a character of length 1 with the experiment name.
`importFun` | a function to read the data files. The default function works for a certain file format, such as that of the example files provided with this package. If your plate reader software produces files with a different format or if you want to import data from a non file-based source, the import function needs to be adapted. See details and examples.
`dec` | Optional argument that is passed to importFun, and can be used to accommodate for data files that use characters different from `.` to represent the decimal point (e.g., the comma `,`).
`verbose` | a logical value, if TRUE, the function reports some of its intermediate progress.
`...` | additional arguments that are being passed on to `filename` if it is a function.

### Details

The plate list is expected to be a tab-delimited file with at least three columns named `Filename`, `Plate`, and `Replicate`. The contents of the columns `Plate` and `Replicate` are expected to be integers. `Filename` should be a vector of file names of the respective raw data files. If the `path` argument is supplied and `importFun` is missing, its value will automatically be prepended to the file names. The optional `Batch` column can be used to supply batch information for an experiment, e.g., when a reagent has been changed or the experiment has been run over several days.

Further columns are allowed, and can be used to denote, for example, different variants of the assay, treatments, incubation times, conditions, etc.

Alternatively, the value of `filename` can be a user-defined function which creates a `data.frame` similar to the one described before. This is for instance useful if the plate list information is directly imported from a data base. In order to allow for non-elementary data types, the output of the function can also be a named list, where each element has to be a vector of equal length. The aforementioned type restrictions still apply. The function will be called with all additional ... arguments, which allows to pass in additional information like experiment identifiers or data base queries.

`importFun` can be used to define a custom function to import data files. The `importFun` function should accept as its first argument names from the `Filename` column of the plate list (which in principle do not need to be individual files, they could also be handles for database entries, queries, or pointers into relevants parts of a file). As it second argument, the function should accept the value of the `path` argument, and the user needs to explicitely prepend this to the file names if needed. It should return a list with two components:

- The first component should be a `data.frame` with the following columns

  - `well`, a character vector with the well identifier in the plate.

  - `val`, the intensity values measured in that well.

  and with as many rows as there are wells in the plate.

- The second component should be a character vector containing a copy of the imported input data file (such as the output of `readLines`). It should be suitable to be used as input for `writeLines`, since it will be used to reproduce the intensity files that are linked in the HTML quality reports generated by `writeReport`.

For example, to import plate data files from EnVision plate reader, set `importFun=getEnVisionRawData` or `importFun=getEnvisionCrosstalkCorrectedData`. See function `getEnVisionRawData`.

Direct data base import without the need for any flat files at all could for instance be achieved by:

- Providing a user-defined function as the `filename` argument and an experiment identifier as an additional ... argument. The function would have to query the data base for the plate information using this identifier and return a table as described above, where the `Filename` column contains identifiers needed to fetch the respective raw data for a single plate in a subsequent query. Alternatively, this could be a data base handle, or the query itself.

- Providing a second user-defined function as the `importFun` argument, which takes the value of the `Filename` column for a single plate and retrieves the respective raw data from the data base.

### Value

An object of class `cellHTS`, which extends the class `NChannelSet`.

After calling this function, the content of the following slots is as follows:

`assayData` | an object of class `AssayData` containing the imported measurement data. Each matrix represents a single channel, and each run corresponds to a column. Thus, the total number of rows in each matrix corresponds to the product between the number of wells per plate and the number of assay plates.
`phenoData` | information about the runs, inferred from the `plateList` file: which replicate, which variant of the assay, treatment, incubation times etc.
`featureData` | the information about the plate and well identifiers for each plate measurement are stored in columns `plate` and `well` of this slot.
`plateList` | a data.frame containing what was read from input file `x`, plus a column `status` of type character: it contains the string "OK" if the data import appeared to have gone well, and the respective error or warning message otherwise.
`intensityFiles` | a list, where each component contains a copy of the imported input data files. Its length corresponds to the number of rows of `plateList`.

### Author(s)

W. Huber huber@ebi.ac.uk, Ligia Bras ligia@ebi.ac.uk, Florian Hahne florian.hahne@novartis.com

### References

Boutros, M., Bras, L.P. and Huber, W. (2006) Analysis of cell-based RNAi screens, Genome Biology 7, R66.

### See Also

To read input files obtained in a HTanalyser plate reader, see `readHTAnalystData`. To build a cellHTS2 object from a data frame, see `buildCellHTS2`.

### Examples

    datadir <- system.file("KcViabSmall", package = "cellHTS2")
    x <- readPlateList("Platelist.txt", "KcViabSmall", path=datadir)

    ## To read data files obtained from an EnVision plate reader:
    datadir <- system.file("EnVisionExample", package = "cellHTS2")
    x <- readPlateList("platelist.txt", name="EnVisionEx",
              importFun=getEnVisionRawData, path=datadir)

    ## to get the cross talk corrected data:
    y <- readPlateList("platelist.txt", name="EnVisionEx",
              importFun=getEnVisionCrosstalkCorrectedData, path=datadir)

[Package cellHTS2 version 2.51.0 Index]