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I have a polygon shapefile (with 4000 records in it) that I want to group into different regions by doing a "select by attribute". I need to do this about 164 times because of the different selection ranges I use in the expression (eg nr >= 1000 AND nr <= 1119). For each new selection I need to calculate the Fieldname(Region) to the name of the new region (again 164 times) How can I achieve this in modelbuilder?

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btw Im totally new ni using modelbuilder and programming – user6014 Feb 20 '12 at 9:20
So you have 164 unique expressions to calculate against? – artwork21 Feb 20 '12 at 15:04
the 4000 records range from 1000 to 4026. I have to select values >=1000 and <=1119 and if this is true, then all these records goes into Region 1. Same calculation for Region 2 but values >=1120 and <=1159. and so on for region3 up to region 164. I also want to make sure that the Region field gets calculated at teh same time eg. if value >=1000 and <=1119, the "calculate field('Region')= 'Region1'. etc etc – user6014 Feb 20 '12 at 15:40

1 Answer

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You state you already know that you have 164 expressions to run, which would give you 164 regions, but each expression varies slightly. So you must have knowledge or a list of the ranges each region will be?

You could use Excel to create a column where each row contains the sql expression you intend to run in the select by attribute tool and save this off as a dbase file where the region number is implied by the row number.

If you are using ArcGIS 10 then you could use a for iterator to step through your dbase and using the field (which would be a string field) to be the expression for the select by attribute and the value to be the region number to assign to the selected fields

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If you're going to use Excel, you might just as well reclassify the [nr] field right then and there! You can do it by setting up a sorted array of breakpoints and indexing into it using VLOOKUP (with the range option set to TRUE). – whuber♦ Feb 20 '12 at 19:01
Thank you for the advise. Also thought to rather do it in Excel. – user6014 Feb 20 '12 at 22:28

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