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I have a shapefile with a field containing floating point numbers ranging from about -200 to 20. Many records have a value of exactly 0. I would like to symbolize the layer as follows:

  • < 0 (green)
  • = 0 (yellow)
  • `> 0 (red)

It looks as though in Symbology > Quantities > Graduated colors only ranges are possible. I first selected three classes and defined the bottom 2 cuttoffs as zero:

enter image description here

However when I try to set the color ramp in the symbology I see that an exact value of 0 is not possible:

enter image description here

Also checking the layer I see that all of my zero values have a red color, which isn't what I want.

How do I force the middle category to be exactly 0, and the top and bottom categories to exclude zero?

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    My only thought is to duplicate the layer twice and add a definition query on each, the first with T10_depth < 0, the second T10_depth = 0 and the 3rd T10_depth > 0 then set each with a single symbol of green, yellow and red respectively. – Michael Stimson Jun 25 at 6:40
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It's possible to do without duplicating the layer. In the Classification dialog click on exclusion:

Data Exclusion Propeties

Setup the query to exclude all values equal to zero.

Then open the Legend tab and select 'Show symbol for excluded data'.

Setup symbology for the zero value.

Return to Classification and set to Manual with 2 classes ensure 0 as the mid value. Edit the Labels and symbols as required:

Layer Properties Now the layer in ArcMap is as follows:

enter image description here

  • 1
    I haven't tried it, but I will assume your method works. What I did instead was define a new field with integer values of either -1, 0 or 1 based on my field of interest and used that to symbolize the layer. Not the best option but I will try your method next time... – user32882 Jun 25 at 14:13

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