R: Sort Associations

sort {arules} | R Documentation

## Sort Associations

### Description

Provides the method `sort` to sort elements in class `associations` (e.g., itemsets or rules) according to the value of measures stored in the association's slot `quality` (e.g., support).

### Usage

    ## S4 method for signature 'associations'
    sort(x, decreasing = TRUE, na.last = NA,
        by = "support", order = FALSE, ...)

    ## S4 method for signature 'associations'
    head(x, n = 6L, by = NULL, decreasing = TRUE, ...)
    ## S4 method for signature 'associations'
    tail(x, n = 6L, by = NULL, decreasing = TRUE, ...)

### Arguments

`x` | an object to be sorted.
`decreasing` | a logical. Should the sort be increasing or decreasing? (default is decreasing)
`na.last` | na.last is not supported for associations. NAs are always put last.
`by` | a character string specifying the quality measure stored in `x` to be used to sort `x`. If a vector of character strings is specified then the additional strings are used to sort `x` in case of ties.
`order` | should a order vector be returned instead of the sorted associations?
`n` | a single integer indicating the number of associations returned.
`...` | Further arguments are ignored.

### Details

`sort` is relatively slow for large sets of associations since it has to copy and rearrange a large data structure. Note that sorting creates a second copy of the set of associations which can be slow and memory consuming for large sets. With `order = TRUE` a integer vector with the order is returned instead of the reordered associations.

If only the top `n` associations are needed then `head` using `by` performs this faster than calling `sort` and then `head` since it does it without copying and rearranging all the data. `tail` works in the same way.

### Value

An object of the same class as `x`.

### Author(s)

Michael Hahsler

### See Also

`associations-class`

### Examples

    data("Adult")

    ## Mine rules with APRIORI
    rules <- apriori(Adult, parameter = list(supp = 0.6))

    rules_by_lift <- sort(rules, by = "lift")

    inspect(head(rules))
    inspect(head(rules_by_lift))

    ## A faster/less memory consuming way to get the top 5 rules according to lift
    ## (see Details section)
    inspect(head(rules, n = 5, by = "lift"))

[Package arules version 1.7-2 Index]