[R] aggregate slow with many rows - alternative?

[Hans-Peter]

Many thanks for all your answers. Converting to a matrix didn't help,
I tried with Hmisc but didn't get anywhere (different summary
functions, multiple levels).

2005/10/14, jim holtman <jholtman at gmail.com>:
> Here is the way that I would do it.  Using 'lapply' to process the list and create a matrix

[snip]

Wow! That's a wonderful suggestion, Your code works just fine with my
data (takes 11 seconds). Thanks a lot, I couldn't have written such
code (reading some help entries now...).

Hans-Peter