[Rd] How to efficiently share data (a dataframe) between R and Java

[Ing. Jaroslav Kuchař]

Dear all,

in our ongoing project we use Java implementations of several
algorithms. We also provide a “wrapper” implemented as an R package
using rJava (https://github.com/jaroslav-kuchar/rCBA). Based on our
recent experiments, the significant portion of time is spent on copying
a dataframe from R to Java. The Java implementation needs access to the
source dataframe. 

I have tested several approaches: calling Java method row-by-row;
serialize the whole data-frame to a temp file and parsing in Java; or
row binding to a single vector and calling a single Java method. Each
approach has its limitations e.g. time-consuming row-by-row copying,
serialization and parsing performance or memory limitations of a single
vector. 

Is there an efficient approach how to copy a dataframe from R to Java
and another one from Java to R?

Thanks for any help you can provide...

Regards,
Jaroslav