# expand.grid: Create a Data Frame from All Combinations of Factor Variables

 expand.grid R Documentation

## Create a Data Frame from All Combinations of Factor Variables

### 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 = 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. `stringsAsFactors` logical specifying if 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

Conversion to a factor is done with levels in the order they occur in the character vectors (and not alphabetically, as is most common when converting to factors).

### References

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

`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)

```