Question

A very simple question:

I am writing and running my R scripts using a text editor to make them reproducible, as has been suggested by several members of SO.

This approach is working very well for me, but I sometimes have to perform expensive operations (e.g. read.csv or reshape on 2M-row databases) that I’d better cache in the R environment rather than re-run every time I run the script (which is usually many times as I progress and test the new lines of code).

Is there a way to cache what a script does up to a certain point so every time I am only running the incremental lines of code (just as I would do by running R interactively)?

Thanks.

Answer 1

## load the file from disk only if it 
## hasn't already been read into a variable
if(!(exists("mytable")){
  mytable=read.csv(...)
}

Edit: fixed typo – thanks Dirk.