# ave: Group Averages Over Level Combinations of Factors

## Description

Subsets of `x[]` are averaged, where each subset consist of those observations with the same factor levels.

## Usage

 `1` ```ave(x, ..., FUN = mean) ```

## Arguments

 `x` A numeric. `...` Grouping variables, typically factors, all of the same `length` as `x`. `FUN` Function to apply for each factor level combination.

## Value

A numeric vector, say `y` of length `length(x)`. If `...` is `g1, g2`, e.g., `y[i]` is equal to `FUN(x[j]`, for all `j` with `g1[j] == g1[i]` and `g2[j] == g2[i])`.

`mean`, `median`.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```require(graphics) ave(1:3) # no grouping -> grand mean attach(warpbreaks) ave(breaks, wool) ave(breaks, tension) ave(breaks, tension, FUN = function(x) mean(x, trim = 0.1)) plot(breaks, main = "ave( Warpbreaks ) for wool x tension combinations") lines(ave(breaks, wool, tension ), type = "s", col = "blue") lines(ave(breaks, wool, tension, FUN = median), type = "s", col = "green") legend(40, 70, c("mean", "median"), lty = 1, col = c("blue","green"), bg = "gray90") detach() ```