qs (version 0.25.1.1)

qcache: qcache

Description

Helper function for caching objects for long running tasks

Usage

qcache(expr, name, envir=parent.frame(), cache_dir=".cache", 
              clear=FALSE, prompt=TRUE, qsave_params=list(), 
              qread_params=list())

Arguments

expr

The expression to evaluate

name

The cached expression name (see details)

envir

The environment to evaluate `expr`

cache_dir

The directory to store cached files in

clear

Set to `TRUE` to clear the cache (see details)

prompt

Whether to prompt before clearing

qsave_params

Parameters passed to `qsave`

qread_params

Parameters passed to `qread`

Details

This is a (very) simple helper function to cache results of long running calculations. There are other packages specializing in caching data that are more feature complete.

The evaluated expression is saved with `qsave` in <cache_dir>/<name>.qs. If the file already exists instead the expression is not evaluated and the cached result is read using `qread` and returned.

To clear a cached result, you can manually delete the associated `qs` file, or you can call `qcache` with `clear=TRUE`. If `prompt` is also `TRUE` a prompt will be given asking you to confirm deletion. If `name` is not specified, all cached results in `cache_dir` will be removed.

Examples

# NOT RUN {
cache_dir <- tempdir()

a <- 1
b <- 5

# not cached
result <- qcache({a + b}, 
                 name="aplusb", 
                 cache_dir = cache_dir,
                 qsave_params = list(preset="fast"))

# cached
result <- qcache({a + b}, 
                 name="aplusb", 
                 cache_dir = cache_dir,
                 qsave_params = list(preset="fast"))

# clear cached result
qcache(name="aplusb", clear=TRUE, prompt=FALSE, cache_dir = cache_dir)
# }