collapse (version 1.2.1)

A4-quick-conversion: Quick Data Conversion

Description

Convert common data objects quickly, without method dispatch and extensive checks:

• qDF and qDT convert vectors, matrices, higher-dimensional arrays and suitable lists to data.frame and data.table respectively.

• qM converts vectors, higher-dimensional arrays, data.frames and suitable lists to matrix.

• mctl and mrtl column- or row-wise convert a matrix to list, data.frame or data.table. They are used internally by qDF and qDT, dapply, BY, etc...

• qF converts atomic vectors to factor (documented on a separate page).

• as.numeric_factor and as.character_factor convert factors, or all factor columns in a list, to numeric or character (by converting the levels).

Usage

qDF(X, row.names.col = FALSE)
qDT(X, row.names.col = FALSE)
qM(X)
mctl(X, names = FALSE, return = "list")
mrtl(X, names = FALSE, return = "list")
as.numeric_factor(X, keep.attr = TRUE)
as.character_factor(X, keep.attr = TRUE)

Arguments

X

a vector, factor, matrix, higher-dimensional array, data.frame or list. mctl and mrtl only take matrices.

row.names.col

should a column capturing names or row.names be added? i.e. when converting atomic objects to data.frame or data.frame to data.table. Can be logical TRUE, which will add a column "row.names" in front, or can supply a name for the column i.e. "column1".

names

logical. Should the list be named?

return

an integer or string specifying what to return. The options are:

Int.		String		Description
1		"list"		returns a plain list
2		"data.frame"		returns a data.frame
3		"data.table"		returns a data.table

keep.attr

logical. TRUE keeps all attributes of factor variables apart from the levels and class attributes (such as variable labels etc.).

Value

qDF - returns a data.frame qDT - returns a data.table qM - returns a matrix mctl, mrtl - return a list, data.frame or data.table qF - returns a factor as.numeric_factor - returns X with factors converted to numeric variables as.character_factor - returns X with factors converted to character variables

See Also

GRP, Collapse Overview

Examples

# NOT RUN {
mtcarsM <- qM(mtcars)                # Matrix from data.frame
mtcarsDT <- qDT(mtcarsM)             # data.table from matrix columns
mrtl(mtcarsM, TRUE, "data.frame")    # data.frame from matrix rows, etc...
qDF(mtcarsM, "cars")                 # Adding a row.names column when converting from matrix
qDT(mtcars, "cars")                  # Saving row.names when converting data.frame to data.table

cylF <- qF(mtcars$cyl)               # Factor from atomic vector
cylF

## Factor to numeric conversions
identical(mtcars,  as.numeric_factor(dapply(mtcars, qF)))
# }