Esri Mapping Center - Ask a Cartographer

Multiple Attributes/Quantity by Category

June 21 2011 | 3 comments
Categories: Symbology

ESRI Cartographers,
I'm having trouble using the multiple attribute / Quantity by Category symbology in ArcMap and ArcScene. I'm trying to symbolize one attribute by size and another attribute by color (e.g. Trees of different sizes according to age (Category), and different colors according to water use (Quantity)). The trouble is that the color ramp I choose doesn't seem to get applied the way I think it should. Things that should be blue turn out reddish. I read somewhere that the vary by color ramp part doesn't change the entire color of the symbol, only the saturation and value (HSV colors). This seems strange that the second attribute wouldn't symbolize independently from the first. Is this the way it works and is there any good work around for it? I will be updating to version 10 in the next couple of weeks so it may be easier than my current version (9.3.1)

Thanks

Mapping Center Answer:

I have never heard of this method of rendering the color ramp. However, once you symbolize the features, you can change the color of the blue by simply clicking on those features that are not the right color on the Symbology tab (once you open the Layer Properties dialog) and changing those colors.

Symbolise By Category & Two Qantities posted by Joseph McGehan on Jul 24 2011 7:00PM

Esri Australia Mining Petroleum clients would like this function too.

In our case
The Category is a mineral. The first quantity is a numeric value for depth; this should drive the symbol size. The second quantity is a numeric value for intensity of the mineral; this should drive the gradient color ramp.

The current traditional symbology model does not allow for this.

Regards

Multiple Attribute Symbology posted by Alex Daniels on Jul 25 2011 8:01AM

The way I've gotten around this problem is to choose the attribute that will determine color as the "category" attribute (water usage in the first example) and assign color symbology manually according to whatever color scheme is appropriate. The "quantity" attribute (age in the first example) would then be used to vary the size of the symbols. This may require creating an index field to classify the water usage attribute into discrete values which can be assigned to categories.

Should work posted by Aileen Buckley on Aug 2 2011 1:35PM

Alexc's suggestion should work -- it did for a test case I just tried.

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