expand.grid               package: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)

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.

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.

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)

