Add min/max to aggregate/aggregate2

[GoogleCodeExporter]

It would be hot if aggregate and aggregate2 supported min/max calculations.

The current need looks something like:
- I have a weblog that I am appending to over time with each day's data.
- I only care about the last 30 days data.
- But - I need to know some event and every time it happens, the growing
weblog file updates that event's time to the current date so as to keep it
current in the 30 day window.

I can picture something like:

cat huge_weblog | aggregate2 -F Date-Field,Data-Field -M Date-Field -S
Data-Field-Counter | drop_older_than_30_day_data > huge_weblog

Where input data looks something like:

Date-Field,Data-Field,Data-Field-Counter
03-19-2009,1,3
03-20-2009,1,1

And output data looks something like:

Date-Field,Data-Field,Data-Field-Counter
03-20-2009,1,4

Original issue reported on code.google.com by jimrenw...@gmail.com on 19 Mar 2009 at 10:11