29.3. Time Series
One of the major problems in the real world is how to handle a series of events that occur in the same time period or in some particular order. The code is tricky and a bit hard to understand, but the basic idea is that you have a table with start and stop times for events, and you want to get information about them as a group.
29.3.1. Gaps in a Time Series
The timeline can be partitioned into intervals, and a set of intervals can be drawn from that partition for reporting. One of the stock questions on an employment form asks the prospective employee to explain any gaps in his record of employment. Most of the time this gap means that you were unemployed. If you are in data processing, you answer that you were consulting, ...