A robust data structure for a histogram of events over time.

Question

Hi all,
I've been thinking for days, I am still lost on how to solve the following:
Let's say that we have a list of events that occur over a certain time interval. Each event has a start timestamp and a finish timestamp. The events occur in no particular order and expand over various length of periods.
With respect to the histogram, we mark the time period of an event occuring with a frequency of one. When events overlap over a time period, we mark that time period with a frequency of number of overlapping events.
Given this raw data, we want to examine the data's frequency under various granularity such as second, minutes, hours, days, weeks, month and years for 60sec, 60min, 24 hrs, 7 days, 4 wks ranges respectively.
So, what is a good intermediate (general) data structure that can store all the various events such that they can be easily transformed to a specific granularity. My goal here is to read the event list once, and histogram of events data with respect to various timeframe can be calculated.
Does a timeline like data strucuture that stores aggregated frequencies solve my problem? With a fine granuarlity say seconds and a long time range, the data structure will bound to overflow.
Any help is greatly appreciated!
Brian

Answer 1

You data structure would be in terms of Classes. You need a class Anevent{
String eventName;
Date startTime;
Date endTime;
In your main program have a Vector object which can store unllimited objects and which would not overflow. Store your event objects as they happen in this Vector. After your time interval of events is completed and you have the final Vector, you can pass the vector object to various methods in your main program to be simple or pass it to specailized graph drawing classes you would have to write to draw various Histograms.