Finding what you want. Sort of.

Try this: Grab a copy of your local white pages (no, not the online version, a paper-and-ink copy!). Find a phone number for ‘J. Smith’. How long did that take? 10-20 seconds maybe? Not very long. Now choose a phone number at random that is likely to be in the phone book, say 321-1234. Using the phone book, find the person who has that phone number. Go on, I’ll wait. How long did that take? What was that? You haven’t found it yet?

Why is it that finding the number for J. Smith in the phone book is faster (much, much faster!) than finding the person in the phone book who has the number 321-1234? Because the phone book entries have been sorted by name. Because the names in the phone book are sorted, if we are looking for Smith, and we open the phone book at, say, Miller, then we know immediately that we needn’t look in the first half of the phone book. We can quickly eliminate large chunks of the phone book from our search. In contrast, when searching for 321-1234, we have no option but to look at every number on every page until we find it (or get to the end and find the number’s not even in there!). Sorting information is critical to be able to find what we want quickly.

Enter the World Wide Web: a large mass of completely unsorted information. How do we find what we want? We need someone to sort it for us. Fortunately NZS.com is working on this never-ending task for web sites relevant to New Zealand, and looking for what you want on the NZS.com site is fast and efficient.

To find out more about some methods computers use to sort lots of information, see the fascinating site Computer Science Unplugged, two authors of which are prominent New Zealand Computer Scientists.