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Symbolizing points with multiple attributes - pie chart style

July 02 2010 | 5 comments
Categories: Symbology

Here is the data set I am trying to symbolize using pie charts.
The fields M_type1, M_type2, M_Type3 contain numeric values which range between 0 and 15.
0- no value.
1-15 refer to different metals present.
Each point would be symbolized using a pie chart symbol. Each slice of the pie chart would be color coded based on the numeric value present in fields M_Type1, M_Type2, M_Type3

Thanks
Bob

Mapping Center Answer:

OK – I think I have this pretty close to what you are trying to do, but not exactly. The remaining problem lies in one small detail – you will have to decide how critically important this is -- I explain it at the end of this answer. In essence, this is the solution: add three layers to your map, one for each of the M_Types (1,2 and 3), symbolize each with a portion of the pie that you want to show and set the colors so that each metal type has a specific color.

To do, that start by creating three styles:

  • M_Type1 style—this will be filled solid circles with a different color for each metal type and the name of the symbol is the same as the number for the metal type (this name will later be used in the Match to Symbol sin a Style function).
  • M_Type2 style—this will be filled half circles with a different color for each metal type (the same colors as for the solid circles) and the name of the symbol is the same as the number for the metal type.
  • M_Type3 style—this will be filled 1/3 circle wedges with a different color for each metal type (the same colors as for the solid circles and the half circles) and the name of the symbol is the same as the number for the metal type.

To create the styles, use character marker symbols that reference the Esri Wedges font – this has various symbols for overlapping parts of pie symbols. I noticed that the filled and half circles overlapped perfectly but I had to apply a 1 pt offset for the 1/3 circle wedges. (to make things easier, I made the first style, then copied and pasted it twice and simply changed the font glyph that was referenced in each of the other two styles, as well as set the offset for the 1/3 pie wedge symbols).

Note that if you want to share this map with others and you want them to see it correctly, they also have to have the Esri Wedges font on their computer, so they will also have to copy it to their font directory.

In order to get the symbols to match the correct colors, you first have to create three new fields in your data set because the M_Type1, 2 and 3 fields are numeric and the match to symbols in a style function will try to match those numbers to the names in the style, which are really text strings. If you do not change the M_Type fields to text fields, the numeric M_type values will be matched to the internal ID of the symbols (which are also numeric) in the style (which is actually an Access database). To calculate the new fields as strings, use the following calculate statement:

Cstr([M_Type1])

(Source for this code: http://www.example-code.com/vb/numberToString.asp)

Now you are ready to apply the symbology – on the symbology tab of the layer properties for the first layer (M_Type1), use the Categories – Match to symbols in a style option, set the value field to the text field for M_Type1 (I called it M_Type1txt, in my test), and set the style to be the M_Type1 style which contains the filled solid circles. Then for the second layer (M_Type2), again use the Categories – Match to symbols in a style option, set the value field to the text field for M_Type2 (I called it M_Type2txt, in my test), and set the style to be the M_Type2 style which contains the filled half circles. Then for the third layer (M_Type3), again use the Categories – Match to symbols in a style option, set the value field to the text field for M_Type3 (I called it M_Type3txt, in my test), and set the style to be the M_Type3 style which contains the ½ pie wedge symbols.

Set the order of the layers in your Table of Contents so that the filled circles are on the bottom, the half circles draw second and the 1/3 pie wedge draw last an on top of the other two layers. You can see the results in the image below.

Example of Pie Charts Symbology

You will see that there is one last problem – all half circles will draw over all filled circles and all wedges will draw over all other symbols, so the overlap is not perfect. However, the only solutions I know for this problem are very time consuming and you would have to reset the properties to make them draw correctly every time you add or delete data from your data set. So if you can live with the funky overlap in some places, you are most of the way to the solution. I think that for a visual analysis of the data, which is what you want to achieve, this solution will likely suffice without the added effort to deal with the overlap.

To help, I will email you a zip file that contains your data, the three styles, and the Esri_wedges font (copy this into your C:\WINDOWS\Fonts directory), as well as an MXD that shows you how I made the map.

Hopefully this will work for you! Good luck!

Where can I download the ESRI Wedge Font? posted by Michael Kolody on Mar 25 2011 11:57AM
This article is great.... I have been wanting to create this exact symbology for some time now, but never thought to change the font style. Now my questions is, Where can I download the Wedge Font????
ESRI Wedge Font posted by Bob Plummer on Mar 25 2011 2:36PM
Hi Micheal:
Send me an e-mail at smartmap@shaw.ca and I can send you the wedge font.
Regards
Bob
Installed with the software posted by Aileen Buckley on Mar 25 2011 3:55PM
It should also be installed with the software so if you use the drop down to select a font, ESRI Wedges should show up.
No Wedges.... posted by Michael Kolody on Mar 28 2011 11:22AM
....not sure why the ESRI Wedges font was not installed on my computer? I have all of the other ESRI fonts in the Windows directory... just no wedges!
My bad posted by Aileen Buckley on Mar 28 2011 11:39AM
My bad -- they are in my list of Esri fonts but I recall now that I loaded them. Therefore, we will post them on Mapping Center's ArcGIS Resources - Styles page for you.

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