expand.grid {base}

R Documentation

Create a Data Frame from All Combinations of Factors

Description

Create a data frame from all combinations of the supplied vectors or factors. See the description of the return value for precise details of the way this is done.

Usage

expand.grid(..., KEEP.OUT.ATTRS = TRUE, stringsAsFactors = FALSE)

Arguments

...	vectors, factors or a list containing these.
KEEP.OUT.ATTRS	a logical indicating the "out.attrs" attribute (see below) should be computed and returned.
stringsAsFactors	If true, character vectors are converted to factors.

Value

A data frame containing one row for each combination of the supplied factors. The first factors vary fastest. The columns are labelled by the factors if these are supplied as named arguments or named components of a list. The row names are ‘automatic’.

Attribute "out.attrs" is a list which gives the dimension and dimnames for use by predict methods.

Note

Prior to R 2.9.0 character vectors were always converted to factors (and this was not documented). stringsAsFactors = TRUE gives the earlier behaviour.

References

Chambers, J. M. and Hastie, T. J. (1992) Statistical Models in S. Wadsworth & Brooks/Cole.

See Also

combn (package utils) for the generation of all combinations of n elements, taken m at a time.

Examples

require(utils)

expand.grid(height = seq(60, 80, 5), weight = seq(100, 300, 50),
            sex = c("Male","Female"))

x <- seq(0,10, length.out=100)
y <- seq(-1,1, length.out=20)
d1 <- expand.grid(x=x, y=y)
d2 <- expand.grid(x=x, y=y, KEEP.OUT.ATTRS = FALSE)
object.size(d1) - object.size(d2)
##-> 5992 or 8832 (on 32- / 64-bit platform)

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