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Hello, Using Model Builder, I created a model that calculates Average Nearest Neighbor scores for a large number of points in a region. They points belong to many sub-regional zones. So I use Iterate Feature Selection to iteratively calculate Average Nearest Neighbor scores for points in each zone. I have attached a screen shot of the model. My problem is as follows: Average Nearest Neighbor tool requires at least two features in a zone to work (of course!). But in my dataset, there are zones that have only one observation. So my model stops when it encounters the first zone that has only one point and gives an error message. I think I can get around this problem by manipulating my dataset, such as deleting those zones/points before running my model and then adding them back in the system after model run for consequent analysis. But I am wondering if it is possible to keep these observations in the dataset, and when the model encounters a zone with only one point, it would not stop but rather either leave a null value for the Nearest Neighbor Score or enter an artificially high number, e.g. 999999 as the score, and continue to process remaining zones/points in the dataset. Having such a feature will help me a lot, since I need to run this model for a number of datasets. Any help would be highly appreciated. Thanks.
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01-24-2012
05:23 AM
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Yes. It works perfectly! One modification: I didn't really need "Collect Values" for this to work, as shown in the attaech chart. Thanks Dan, for all your timely help!
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01-13-2012
04:17 AM
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Thank you very much! Looks very promising. But I am stuck with one little thing - where to find "select by attributes" tool for Model Builder? I can find other selection tools such as 'select layer by attributes' but had no luck to find the most popular 'select by attributes' for model builder. Please let me know if you know where to get it. Thanks again!
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01-12-2012
05:45 PM
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I have tens of thousands of points in a region. I divide the region into over 2,000 sub-regional zones, and assign a zone ID to each point. I want to calculate a spatial clustering score of the points in each zone. Using Model Builder in ArcGIS, I build a model that has two major components: "Average Nearest Neighbor" tool and "Iterate Feature Selection" tool. It iteratively selects points by zone ID and calculates Nearest Neighbor Ratio (NNRatio) for the points in each zone. The results are just what I need. The problem is that I can only see the results in the progress dialogue box on the screen with all sorts of unwanted info (e.g. "processing begins ...") for each iteration. I really need a way to get a clean output table that has zone ID and NNRatio fields. I tried "Collect Values" tool. It can collect Zone IDs and NNRatios (separately), but it doesn't create a file. Again, I can only view results on the screen, although it is cleaner without all the other info on processing progress. Average Nearest Neighbor function has an option to export a HTML report. But it is HTML, one file for each zone, and with a lot of unnecessary info and graphics. So my question is if there is a way to get an output table with zone IDs and NNRatios. Any help would be greatly appreciated.
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01-12-2012
08:10 AM
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