inst/doc/usingSimpleRCache.R

In simpleRCache: Simple R Cache

## ----setup, echo=FALSE, warning=FALSE, message=FALSE--------------------------
require("knitr")
opts_knit$set(root.dir="..")
opts_chunk$set(fig.align="center", fig.width=6, fig.height=6, dpi=300)

## ----example, message=FALSE, warning=FALSE------------------------------------
# Example function to cached
fib <- function(n) {
 
    # Handle "vectors" by element
    if (length(n) > 1) {
        return(sapply(n, fib))
    }
 
    # Base cases
    if (n == 0) 
        return(0)
    if (n == 1) 
        return(1)
 
    # Check to see if n is an integer Do not use is.integer as that is very
    # strict
    if (round(n, 0) != n) 
        return(NA)
 
    # Negative numbers
    if (n < 0) 
        return(fib(-1 * n) * ((-1)^((n + 1)%%2)))
 
    # Everything else
    return(fib(n - 1) + fib(n - 2))
}

library(simpleRCache)

setCacheRootPath()

fibCached <- addMemoization(fib)

nums <- -25:25
 
system.time(fibResults <- fib(nums))
system.time(fibResults1 <- fibCached(nums))

# Second run should be cached
system.time(fibResults2 <- fibCached(nums))

identical(fibResults, fibResults2)
identical(fibResults1, fibResults2)

## ---- eval=FALSE--------------------------------------------------------------
#  sessionInfo()