grepEcols {MSnbase} | R Documentation

## Returns the matching column names of indices.

### Description

Given a text spread sheet `f` and a `pattern` to be matched to its header (first line in the file), the function returns the matching columns names or indices of the corresponding `data.frame`.

### Usage

    grepEcols(f, pattern, ..., n = 1)

    getEcols(f, ..., n = 1)

### Arguments

`f` | A connection object or a `character` string to be read in with `readLines(f, n = 1)`.
`pattern` | A `character` string containing a regular expression to be matched to the file's header.
`...` | Additional parameters passed to `strsplit` to split the file header into individual column names.
`n` | An `integer` specifying which line in file `f` to grep (get). Default is 1. Note that this argument must be named.

### Details

The function starts by reading the first line of the file (or connection) `f` with `readLines`, then splits it according to the optional `...` arguments (it is important to correctly specify `strsplit`'s `split` character vector here) and then matches `pattern` to the individual column names using `grep`.

Similarly, `getEcols` can be used to explore the column names and decide for the appropriate `pattern` value.

These functions are useful to check the parameters to be provided to `readMSnSet2`.

### Value

Depending on `value`, the matching column names of indices. In case of `getEcols`, a `character` of column names.

### Author(s)

Laurent Gatto

### See Also

`readMSnSet2`

[Package MSnbase version 2.4.2 Index]