If you're like me, you probably find yourself writing some variation of the following routine in order to avoid unnecessarily performing heavy computations multiple times, across instances of R:

init <- function () {
  # do some calculation
  2 * 2 # dummy result
}

if (!exists("test")) { # Do nothing if variable exists in environment
  file <- "test.RData"
  if (!file.exists(file)) {
    load("test.RData") # Load workspace that contains the variable
  } else {
    test <- init() # Compute content of variable by calling a zero argument function
    save("test", "test.RData") # Save variable into workspace
  }
}

I wrote the xache function to be able to simplify this process to the following bit of code:

xache("test", "test.RData", init)

xache("test", "test.RData", function () {
  # do some calculation
  2 * 2 # dummy result
})

xache works as follows:

1. If the specified variable exists, nothing happens because there is no need to recompute its contents.
2. If it the variable does not exist, xache will attempt to load it from the specified RData file.
3. If the RData file does not exist, the specified function will evaluate the specified function, and store its results in the specified variable as well as in the RData file.

install.packages("devtools")
library("devtools")
devtools::install_github("ndejay/xache")
library("xache")

Copyright (c) 2016 Nicolas De Jay

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