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Thanks for the answers guys, I appreciate you taking the time to help me out. Dan
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02-11-2013
02:01 AM
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Hi Michael, Thanks for the link, it's interesting reading. When it came to applications within ArcGIS I suspected that it wouldn't necessarily be directly implementable. Yes, I did think that VRP might be the way to do it, I've been experimenting with setting capacities and pick ups as binary constraints for a route between fixed "depots", but have yet to figure out the exact work around. Any advice you have would be greatly received. The specific application I'm interested is related to the an individual's food environment and the notion of 'trip chaining', so I'm hoping to get a sense of the area of opportunity, or activity, for individuals who might wish to visit a set of particular types of food store (i.e. markets, butchers, grocers, discount retailers etc.) from their home location, or between paired locations like home-school, home-work. I'm exploring the idea that you could derive a measure of opportunity, or efficiency, by looking at the extent to which particular chains deviate from least cost routes, and how this might relate to behaviours. In this sense we're talking a limited number of types, maybe 3 to 5, but within each type there is the potential for a largish number of facilities (up to 50 for a constrained local area, or particular route) depending on the local density of food stores.
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02-07-2013
08:40 AM
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Yes, happy with model builder. I've a python geoprocessing solution for the the problem, but it's brute force, and as you might expect it rapidly falls over as the number of facilities or number of classes of facilities rises! Many Thanks!
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02-05-2013
06:57 AM
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The usual issue here, particularly with line geometries that you've digitised yourself, is one of connectivity. Although edges may appear to meet at vertices, they may not, even if the gap is very small this will not necessarily be recognised as a mutual vertex when you build a network from that line geometry. Try running the snap (Editing) tool, with a suitably low value and try again. If that fails, try the Integrate tool. Then rebuild the network from the revised geometry. The fields themselves should be fine, assuming the values are appropriate, you'll need to add the oneway restriction when designing the network.
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02-05-2013
03:57 AM
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Hello, For a given individual, I'm looking to create the least cost route that would take in 1 of each kind of facility in my dataset. Let's assume I have 10 facilities of 5 types, with 2 facilities in each type. I would like to return a distance in which one of each of those 5 types of facilities is visited, in any order, finishing either: 1) back at the origin point, which is distinct from the facilities, 2) at a different destination point, that is again distinct from the facilities, or 3) At the final point of the facilities to be visited. One of each of the types of facilities must be visited, so there would be 5 total visits, and in this case, 5 facilities would not be visited as visiting them does not fall on the shortest path. Is this possible? It strikes me that this is like a travelling salesman problem: rather than visit each city in a set of regions, the salesman must visit just 1 city per region in a set of regions containing many cities. Thanks in advance, Dan
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02-04-2013
06:50 AM
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