RE: [PHP] Seeking overlap algorithm

On 07 December 2007 02:14, tedd wrote: > Now, what I need is a way to analyze the distribution of the current > service providers to see if a given location is open to being sold as > a "preferred" position -- do you see what I mean? > > Another example, let's say we have four "preferred" service providers > at the same location. Obviously, we could not sell another > "preferred" position within 100 miles. > > Another example, let's say we have four "preferred" service providers > 100 miles apart, clearly we can sell more "preferred" positions. But, > the number of positions available depends upon the distribution of > the original four. If they were located in a straight line, then we > could sell two positions between each one. But, if they were > distributed in a square, we could only sell one. Do you see? A simplistic but effective way would be: (1) Locate all "preferred" providers within 50 miles of the potential new one (presumably a maximum of four!). (2) For each of these, find how many suppliers are within their 50-mile catchment radius. If any of the answers at step 2 is four, you lose; if none of them is, you win. I can't think of any obvious ways to optimize this, but then I never did properly "get" the travelling salesman or 4-colour problem! Cheers! Mike --------------------------------------------------------------------- Mike Ford, Electronic Information Services Adviser, JG125, The Headingley Library, James Graham Building, Leeds Metropolitan University, Headingley Campus, LEEDS, LS6 3QS, United Kingdom Email: m.ford@leedsmet.ac.uk Tel: +44 113 812 4730 Fax: +44 113 812 3211 To view the terms under which this email is distributed, please go to http://disclaimer.leedsmet.ac.uk/email.htm