If a function is called multiple times with the same input, you can
often speed things up by keeping a cache of known answers that it can
retrieve. This is called memoisation http://en.wikipedia.org/wiki/Memoization.
The memoise package provides a simple syntax
mf <- memoise(f)
to create mf(), a memoised wrapper around f(). You can clear mf's
cache with
forget(mf)
, and you can test whether a function is memoised with
is.memoised(mf) # TRUE
is.memoised(f) # FALSE
.