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Creating range symbology for lines

November 10 2009 | 0 comments
Categories: Symbology

I edited line data (water mains) in a geodatabase and changed the labeling from the function attribute to the diameter attribute to reflect in the legend. Since we have multiple sizes of main, we have grouped some of them into diameter ranges to have the same color (i.e., 10-12", 14-20", etc.) When I changed the range in the layer symbology tab, the already edited mains with a diameter of 16" (or any other diameter grouped) converted to "other." Is it possible to set a range so previously edited lines will know what group to go in? Is this a script I have to write or can it easily be changed in ArcMap Layer Properties?

Mapping Center Answer:

Yes.  There are two ways:

1.  Since you are working in a geodatabase, you can predefine the valid diameters in a coded value domain. When you use unique values symbology with that field, all the possible values will be shown, even if you have not created a feature for some of them.  You can select multiple rows in the unique values table, and group them you would like as well.

2.  A little more difficult is to use the Add Values button in the unique values symbology.  Here you can type a new value, for instance, 3.5" and then click the Add to List button.  Repeat as needed, then select those values in the list and click OK.  This is harder because you have to conform to what you chose for your list.

In both cases, this depends on using unique values symbology, which is typically what I see used for water mains data.



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