aggregate-methods {S4Vectors} | R Documentation

## Compute summary statistics of subsets of vector-like objects

### Description

The S4Vectors package defines `aggregate` methods for Vector, Rle, and List objects.

### Usage

    ## S4 method for signature 'Vector'
    aggregate(x, by, FUN, start=NULL, end=NULL, width=NULL,
              frequency=NULL, delta=NULL, ..., simplify=TRUE)

    ## S4 method for signature 'Rle'
    aggregate(x, by, FUN, start=NULL, end=NULL, width=NULL,
              frequency=NULL, delta=NULL, ..., simplify=TRUE)

    ## S4 method for signature 'List'
    aggregate(x, by, FUN, start=NULL, end=NULL, width=NULL,
              frequency=NULL, delta=NULL, ..., simplify=TRUE)

### Arguments

`x` | A Vector, Rle, or List object.
`by` | An object with `start`, `end`, and `width` methods. If `x` is a List object, the `by` parameter can be a IntegerRangesList object to aggregate within the list elements rather than across them. When `by` is a IntegerRangesList object, the output is either a SimpleAtomicList object, if possible, or a SimpleList object, if not.
`FUN` | The function, found via `match.fun`, to be applied to each subset of `x`.
`start, end, width` | The start, end, and width of the subsets. If `by` is missing, then two of the three must be supplied and have the same length.
`frequency, delta` | Optional arguments that specify the sampling frequency and increment within the subsets (in the same fashion as `window` from the stats package does).
`...` | Optional arguments to `FUN`.
`simplify` | A logical value specifying whether the result should be simplified to a vector or matrix if possible.

### Details

Subsets of `x` can be specified either via the `by` argument or via the `start`, `end`, `width`, `frequency`, and `delta` arguments.

For example, if `start` and `end` are specified, then:

      aggregate(x, FUN=FUN, start=start, end=end, ..., simplify=simplify)

is equivalent to:

      sapply(seq_along(start),
             function(i) FUN(x[start[i]:end[i]], ...), simplify=simplify)

(replace `x[start[i]:end[i]]` with 2D-style subsetting `x[start[i]:end[i], ]` if `x` is a DataFrame object).

### See Also

- The `aggregate` function in the stats package.

- Vector, Rle, List, and DataFrame objects.

- The `start`, `end`, and `width` generic functions defined in the BiocGenerics package.

### Examples

    x <- Rle(10:2, 1:9)
    aggregate(x, x > 4, mean)
    aggregate(x, FUN=mean, start=1:26, width=20)

    ## Note that aggregate() works on a DataFrame object the same way it
    ## works on an ordinary data frame:
    aggregate(DataFrame(state.x77), list(Region=state.region), mean)
    aggregate(weight ~ feed, data=DataFrame(chickwts), mean)

    library(IRanges)
    by <- IRanges(start=1:26, width=20, names=LETTERS)
    aggregate(x, by, is.unsorted)

[Package S4Vectors version 0.20.1 Index]