Monthly Archives: April 2009

Unraveling the Four-Digit ZIP Code Mystery


Map of New England

Since the U.S. Post Office standardizes to five digits and ZIP+4, having a great many four-digit ZIP Codes in the 2008 student dataset was a problem. After comparing the “short” ZIP Codes to each student’s city and state, I discovered the problem. All the four-digit ZIP Codes were in New England, where many ZIP Codes start with 0—and our native student database drops leading zeros.

The ZIP Code data was stored in a string field (Customer_Zipcode), which would not sort in a way to make the four-digit ZIP Codes stand out (and so be easily selectable). To fix this, I created a new short integer field called ZIPasNum, then used the Field Calculator to populate the ZIP Codes from the string field into the new one: [ZIPasNum]= [Customer_Zipcode].

An interesting note on the short integer field is that ZIP Codes interpreted as being higher than the value 32,767 were rejected (given null values). This was OK because I was only interested in finding four-digit ZIP Code records anyway.

With the ZIP Codes in number format, I could:

  • Sort the data to find and select values less than 10,000, which would be any records that were missing the first digit (or two in a few cases).
  • Use the Field Calculator on the selected set to add 0 to the beginning of each ZIP Code (“0” ++ [Customer_Zipcode]).
  • Copy the corrected ZIP Codes back to the string field, Customer_Zipcode.


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Spring Reading Suggestions for GIS Users


In the current edition of ArcUser Online a couple of articles caught my eye. In The Top Nine Reasons to Use a File Geodatabase, Colin Childs, an instructor with ESRI Educational Services, makes the case that the file geodatabase is a better choice for storing geospatial data than shapefiles and the Microsoft Access-based personal geodatabase (.MDB format).

Colin includes several tables with key information about the file geodatabase and tips for data migration and storage. Colin also clarifies the difference between compacting a geodatabase and compressing a geodatabase. If you haven’t yet used the file geodatabase, this article may persuade you to give it a try. Continue reading

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A Flex-ible Web Mapping Solution

July 19, 2012 update: The Flex Sample Viewer referenced below has been replaced with the ArcGIS Viewer for Flex. You can learn more about and download the latest viewer on the ArcGIS Resource Center.


In a previous post, we showed how to create a quick mashup using the ArcGIS API for Flex and free sample services from ArcGIS Online. Now there’s another option designed for GIS professionals who want to create a high-performing web mapping application but don’t have extensive programming skills. Continue reading

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Serve Yourself at the Training Bar


How to evolve our training products to best meet user needs is a continuing discussion among the folks at Esri Training Services. We are always talking about how we might deliver GIS training more efficiently, more effectively, more creatively…you get the idea. While we have some great ideas in the works, they take time to percolate out to the masses. I got to thinking: if users could create their own training experience… Continue reading

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