topic Problems with proportional symbology and point data! in Mapping Questions

Problems with proportional symbology and point data!

TimMiller — Fri, 31 Jul 2015 22:56:49 GMT

Running ArcGIS 10.3 for Desktop, with an "Advanced" license type.

What I'm trying to do: I am trying to display point data via proportional symbols based on a Square Footage attribute. The square footage value is missing for some data points, while for others the value is so small it's impossible to see on the map. I am trying to get it so it will display all values proportionally, except for NULL values and values less than about 10 square feet, both of which I would like to be displayed with normal points.

How I'm Trying to Do it....: I am setting the feature class' symbology to Proportional (Properties -> Symbology -> Quantities -> Proportional Symbols), with Value: WeedArea, Unit: Feet, and Data Represents: Area. To get the points with small and/or null values for WeedArea to display as normal points instead of proportional symbols, I use the "Exclude..." option which is in that same Proportional Symbols settings page.

The Exclude option basically just opens a query builder. I have "Show symbol for excluded data" selected on the "Legend" tab, and in the "Query" tab, I am using the expression WeedArea IS NULL OR WeedArea < 10. Clicking the "Verify" button says everything is good to go.

The Problem: It isn't working how I'd expect.

- If I use the above expression, it displays everything that matches the exclude query as normal point features (which is what I want). However, it also then hides all the points that should be displayed by proportional symbols (i.e., everything that did NOT match the exclude query). This is a problem! Why is it doing this?????

- If I instead just do a single conditional and don't have any "OR" statement (e.g., I type only "WeedArea IS NULL" or instead only "WeedArea < 10") then it works correctly - it displays the data as expected with proportional symbols for everything that doesn't match the Exclude statement, and normal point symbols for everything that DOES match the exclude statement.

I would REALLY appreciate any help with this. Is this not possible with ArcMAP? Is it a bug? Is there something I'm doing wrong?

Re: Problems with proportional symbology and point data!

JayantaPoddar — Sun, 02 Aug 2015 22:36:37 GMT

Hi Tim,

I tried reproducing the issue. This is what I observed.

When you set "Data Represents" option to area, the value was applied to the size of the symbol area.

The symbols are too small to observe at a smaller scale. I could see it once I zoom into one of the points.

If not necessary, try to use the default unit (unknown) for representing proportional symbols.

Re: Problems with proportional symbology and point data!

TimMiller — Mon, 03 Aug 2015 19:04:13 GMT

Thanks for experimenting Jayanta! Unfortunately this isn't the issue for me.

Like I mentioned, when I use only one conditional, the symbols show up just fine, accurately representing area. The problem only arises when I use 2 conditional statements. The issue affects all points, including those with very large areas (e.g, 40,000 square feet) and the points to not appear when I zoom way in or out, so I do not believe that the symbols simply being too small to see is the issue. Also, unfortunately in this case it is important for us for the symbols to represent area rather than generic units so switching that is not an option for us.

Re: Problems with proportional symbology and point data!

TimMiller — Mon, 03 Aug 2015 19:07:49 GMT

To clarify, Jayanta, when you tried to reproduce, did you have a two parted conditional statement similar to mine? E.g., "WeedArea IS NULL OR WeedArea < 10." And it worked for you? (apart from some of the symbols being too small to see)

Re: Problems with proportional symbology and point data!

IanMurray — Mon, 03 Aug 2015 19:11:31 GMT

Why not make another field called label, and set it equal to your existing field, then use a selection to find all values less than 10 sq ft and use field calculator to make them NULL just for the purposes of labelling? That way you only need one statement.

Re: Problems with proportional symbology and point data!

TimMiller — Mon, 03 Aug 2015 22:21:03 GMT

Hmm that's not a bad work around. I was hoping that maybe something was askew and that sort of thing could be avoided, however. We have a lot of data in our attribute table and that's just one more thing which I would prefer to avoid. But thanks for the idea! If we can't figure out anything else we may go that route.

Re: Problems with proportional symbology and point data!

JayantaPoddar — Tue, 04 Aug 2015 05:43:55 GMT

Yeah! I used a similar statement and it worked without any fuss (the size of many points just got too small to see). I zoomed to one point to a scale of 1000. Then applied the condition on symbology. I could see the point which had a value of more than 10.)

Re: Problems with proportional symbology and point data!

TimMiller — Tue, 04 Aug 2015 17:30:57 GMT

So, new bit of information. It appears to be a bug in ArcMap 10.3.

If I save this map as an ArcMap 10.2 document (instead of normal 10.3) and then open the map on a computer that only has ArcMap 10.2 installed, everything displays correctly in Arc v10.2. If I go back to the computer with ArcMap v10.3 and try both the 10.2 and the 10.3 versions of the map document, the display problem is there again.

I only have 10.3 and not 10.3.1, so I wonder if this is a bug that was fixed in v10.3.1

Jayanta, precisely which version of Arc did you test this on? 10.3.1? 10.3? 10.2?

Re: Problems with proportional symbology and point data!

JayantaPoddar — Tue, 04 Aug 2015 19:45:20 GMT

Hmmm, it could be a bug then. I did it in ArcGIS 10.1 SP1.

Re: Problems with proportional symbology and point data!

TimMiller — Wed, 05 Aug 2015 20:55:35 GMT

After communicating directly with ESRI, I have confirmed that this was an unknown bug and it has been logged as such for fixing. Hopefully the next version of Arc will have the fix.