cache: Cache a data set for faster loading.

Description

This function will store a copy of the named data set in the cache directory. This cached copy of the data set will then be given precedence at load time when calling load.project. Cached data sets are stored as .RData or optionally as .qs files.

Usage

cache(variable = NULL, CODE = NULL, depends = NULL, tidyCODE = TRUE, ...)

Value

No value is returned; this function is called for its side effects.

Arguments

variable: A character string containing the name of the variable to be saved. If the CODE parameter is defined, it is evaluated and saved, otherwise the variable with that name in the global environment is used.
CODE: A sequence of R statements enclosed in {..} which produce the object to be cached. Requires suggested package formatR.
depends: A character vector of other global environment objects that the CODE depends upon. Caching will be forced if those objects have changed since last caching
tidyCODE: A logical scalar specifying if the CODE shall be tidied with the help of tidy_source. As, for example, whitespace changes do not change the meaning of the code and therefore should not invalidate the cache, this usually is a desired feature. However, in case the CODE contains, for example, complex SQL statements this might fail and skipping this step is an even more desirable feature.
...: Additional arguments passed on to save or optionally to qsave. See project.config for further information.

Details

Usually you will want to cache datasets during munging. This can be the raw data just loaded, or it can be the result of further processing during munge. Either way, it can take a while to cache large variables, so cache will only cache when it needs to. The clear.cache("variable") command can be run to flush individual items from the cache.

Calling cache() with no arguments returns the current status of the cache.

Examples

Run this code

library('ProjectTemplate')
if (FALSE) create.project('tmp-project')

setwd('tmp-project')

dataset1 <- 1:5
cache('dataset1')

setwd('..')
unlink('tmp-project')