PSTricks: readdata and additional data

Hi all,

drawing some diagrams I run into the problem that some of the data to display comes from a file whereas an other part of the data is calculated with LaTeX or PerlTeX.
How do I combine data coming from those different sources?
I guess there is a possibility to change the array \readdata creates. But I didn't manage to find the way to add data to the array.

%% somehow manipulate \dataToDisplay

thanks in advance