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I have to make a thematic map with an attribute table with duplicated features but different attributes. See below:

FEATURE   ATTRIBUTE
-------------------
1         bl
1         gr
2         gr
2         re
3         re
4         bl
5         ye
5         ye

Does anyone knows how to paint a feature (polygon) with the corresponding colors? I mean like for feature 1 paint half blue and half green, for feature 2 half green half red... Thanks.

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Is there a maximum number of possible colors per polygon? Do the polygons form a continuous fabric? – BrianPeasley Jan 20 '11 at 23:57
I have a total of 16 possible colors and I dont understand your second question. – eiefai Jan 21 '11 at 0:43
Re the second question: Do the edges of the polygons all touch each other to form a continuous surface, or are they distinctly separate polygons like lakes. – BrianPeasley Jan 21 '11 at 2:07
They are separated. Thanks for the aclaration. – eiefai Jan 21 '11 at 3:00
...Like lakes... – eiefai Jan 21 '11 at 3:00

4 Answers

up vote 2 down vote accepted

You have a couple billion possible color combinations... I guess hash symbols are out of the question! I think that I would use pie charts.
If you add 16 new attributes to your table and name each field for a color. Then you can give each attribute a value of 1 if the feature should have that color. When you set up your pie chart, you need to make sure that the symbol for the "Red" attribute is indeed red, etc.
Now when you add the pie charts if there is a "1" value in both the "Blue" and "Green" your pie chart will be 50/50 Blue and Green... If you have a "1" value in all 16 color attributes, you will get a beautiful rainbow pizza with even slices.

The image below is what I'm describing: alt text

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This could work. Thanks. – eiefai Jan 21 '11 at 17:21
up vote 2 down vote

Probably not without doing quite a bit of calculating, splitting polygons, and manual color-value mapping.

Having said that I did play with the gradient fill a bit. and came up with this...

gradient filll properties

but if your polys aren't square you will have some problems with that...

makes it ugly

If this is a once in your lifetime dataset and you won't ever have to pull in new data. I would split each polygon (copy of the original file), by the number of colors you want in the box.

If this is data that you will have to re-do, update, show again, I would first create a unique id, (not the internal oid) and then do my splits.

Edit: 1-22 Just had another thought.

Use the unique value, many fields.
Will that give you something close? alt text

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Luckily most of my polygons are squared, but, What do I have to do after what you said to generate a thematic map? I'm still a noob. – eiefai Jan 21 '11 at 17:24
I think if they are square-ish. The suggested above is only a quick and dirty(very dirty) method. see bottom of question above. – Brad Nesom Jan 23 '11 at 1:17
up vote 1 down vote

Quick and dirty method: use hashes at different angles (allowing you to see through them).

alt text

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up vote 0 down vote

I often solve that kind of problem with a "line fill symbol" adjusting separation and offsets, e.g. 10pt line width / 20 pt separation / 10 pt offset of overlapping features. although, more than 3 overlapping features visualized with that method look confusing and aren't easily readable.

screenshot of symbol properties: http://dl.dropbox.com/u/2093991/line_symbol_offset.png

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Thanks cspanring, Is there any way of doing this on the fly (without messing with the simbol properties)? – eiefai Jan 21 '11 at 17:17
The thing is that in your way each polygon can be painted with only two colors, some of my polygons have 3, 4 or more colors. – eiefai Jan 21 '11 at 17:18
I think I've used this method for showing up to 5 categories on overlapping polygons. It's a matter of incrementing separation and offset for each additional category. I'm not aware of an "on the fly" method. A quick ArcPy Layer object check (goo.gl/5cD44) wasn't very successful either. – cspanring Jan 22 '11 at 0:32

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