bit64 (version 4.5.2)

hashcache: Big caching of hashing, sorting, ordering

Description

Functions to create cache that accelerates many operations

Usage

hashcache(x, nunique=NULL, ...)
sortcache(x, has.na = NULL)
sortordercache(x, has.na = NULL, stable = NULL)
ordercache(x, has.na = NULL, stable = NULL, optimize = "time")

Value

x with a cache that contains the result of the expensive operations, possible together with small derived information (such as nunique.integer64) and previously cached results.

Arguments

x

an atomic vector (note that currently only integer64 is supported)

nunique

giving correct number of unique elements can help reducing the size of the hashmap

has.na

boolean scalar defining whether the input vector might contain NAs. If we know we don't have NAs, this may speed-up. Note that you risk a crash if there are unexpected NAs with has.na=FALSE

stable

boolean scalar defining whether stable sorting is needed. Allowing non-stable may speed-up.

optimize

by default ramsort optimizes for 'time' which requires more RAM, set to 'memory' to minimize RAM requirements and sacrifice speed

...

passed to hashmap

Author

Jens Oehlschlägel <[e-mail]>

Details

The result of relative expensive operations hashmap, ramsort, ramsortorder and ramorder can be stored in a cache in order to avoid multiple excutions. Unless in very specific situations, the recommended method is hashsortorder only.

See Also

cache for caching functions and nunique.integer64 for methods benefiting from small caches

Examples

	x <- as.integer64(sample(c(rep(NA, 9), 1:9), 32, TRUE))
 sortordercache(x)