MSnbase: reduce-data.frame-method – R documentation

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reduce-data.frame-method

Reduce a data.frame

Description

Reduce a data.frame so that the (primary) key column contains only unique entries and other columns pertaining to that entry are combined into semicolon-separated values into a single row/observation.

Usage

## S4 method for signature 'data.frame'
reduce(x, key, sep = ";")

Arguments

`x`	A `data.frame`.
`key`	The column name (currenly only one is supported) to be used as primary key.
`sep`	The separator. Default is `;`.

Details

An important side-effect of reducing a 'data.frame' is that all columns other than the key are converted to characters when they are collapsed to a semi-column separated value (even if only one value is present) as soon as one observation of transformed.

Value

A reduced data.frame.

Author(s)

Laurent Gatto

Examples

dfr <- data.frame(A = c(1, 1, 2),
                  B = c("x", "x", "z"),
                  C = LETTERS[1:3])
dfr
dfr2 <- reduce(dfr, key = "A")
dfr2
## column A used as key is still num
str(dfr2)
dfr3 <- reduce(dfr, key = "B")
dfr3
## A is converted to chr; B remains factor
str(dfr3)
dfr4 <- data.frame(A = 1:3,
                   B = LETTERS[1:3],
                   C = c(TRUE, FALSE, NA))
## No effect of reducing, column classes are maintained
str(reduce(dfr4, key = "B"))

MSnbase

Base Functions and Classes for Mass Spectrometry and Proteomics

v2.16.1

Artistic-2.0

Authors

Laurent Gatto, Johannes Rainer and Sebastian Gibb with contributions from Guangchuang Yu, Samuel Wieczorek, Vasile-Cosmin Lazar, Vladislav Petyuk, Thomas Naake, Richie Cotton, Arne Smits, Martina Fisher, Ludger Goeminne, Adriaan Sticker and Lieven Clement.

Initial release