[R] Dynamic Dictionary Data Type?

[Thomas Lumley]

On Thu, 2 Jun 2005, hadley wickham wrote:

>> cache results.  Other languages usually offer a dictionary data type
>> which I can use as an efficient way to dynamically cache already
>> calculated results - what's the best way to do this in R?
>
> It really depends on what sort of data you want to cache - if it is
> fundamentally 1D, use a vector, 2D use a matrix etc.  The closest
> equivalent to dictionary/hashmap is a list - however R's pass a copy
> semantics might slow things down if you are caching a lot of data.
>

An environment is a hash table, and copying occurs only on modification, 
when any language would have to copy in this context.

 	-thomas