loadCache {R.cache} | R Documentation |
Loads data from file cache, which is unique for an optional key object.
## Default S3 method: loadCache(key=NULL, sources=NULL, suffix=".Rcache", removeOldCache=TRUE, pathname=NULL, dirs=NULL, ...)
key |
An optional object from which a hexadecimal hash code will be generated and appended to the filename. |
sources |
Optional source objects. If the cache object has a timestamp older than one of the source objects, it will be ignored and removed. |
suffix |
A character string to be appended to the end of the
filename. |
removeOldCache |
If TRUE and the cache is older than the
sources , the cache file is removed, otherwise not. |
pathname |
The pathname to the cache file. If specified,
arguments key and suffix are ignored. Note that
this is only needed in order to read a cache file for which
the key is unknown, for instance, in order to investigate
an unknown cache file. |
dirs |
A character vector constituting the path to the
cache subdirectory to be used. If NULL , the root path is used. |
... |
Additional argument passed to load (). |
The hash code calculated from the key
object is a
32 characters long hexadecimal MD5 hash code. For more details,
see the digest package.
Returns an R object or NULL
, if cache does not exist.
To make use of the key
argument, the digest package
(available on CRAN) must be installed, otherwise an error is generated.
That package is not required when key==NULL
.
Henrik Bengtsson (http://www.braju.com/R/)
saveCache
().
The cache
method in Bioconductor.
simulate <- function(mean, sd) { # 1. Try to load cached data, if already generated key <- list(mean, sd) data <- loadCache(key) if (!is.null(data)) { cat("Loaded cached data\n") return(data); } # 2. If not available, generate it. cat("Generating data from scratch...") data <- rnorm(1000, mean=mean, sd=sd) Sys.sleep(1) # Emulate slow algorithm cat("ok\n") saveCache(data, key=key, comment="simulate()") data; } data <- simulate(2.3, 3.0) data <- simulate(2.3, 3.5) data <- simulate(2.3, 3.0) # Will load cached data # Clean up file.remove(findCache(key=list(2.3,3.0))) file.remove(findCache(key=list(2.3,3.5)))