# Sum of areas in all each polygon layer?

I've got several layers/feature classes in an ArcMap 10 project.

Thanks to everyone's help, I'm able to get the areas for the polygons contained within each layer.

By opening the attribute tables for each layer, and right-clicking on the SHAPE_area column, I can obtain the total area for all the polygons in that layer.

Is there a way to summarise the total areas for ALL of my polygon layers? Or do I have to do it manually for each one? Thanks!

P.S. Just to illustrate, suppose I have layers A, B, and C, all of which contain multiple polygons. Right now, I have to right-click on each layer, open its Attribute Table, right click on the "SHAPE_area" field, click on Summarize (or Statistics), see the sum of all the cells, and manually copy that into a waiting Excel spreadsheet.

Is there a "global" Summarize function so that I can get output like this (formatted to be comma delimited)?

Layer, area

A, 12

B, 13

C, 5

Right click the field you want to summarize and hit statistis or summarize. Hope it works Jorge

• Thanks for the answer. Yes I've been able to do that. But I like to do it for all my feature classes (that have the field SHAPE_area) at once, because I have so many of them. Is there a way to do that? Editing orig. question to clarify. – hpy Apr 4 '11 at 21:53
• Merge all the layers into a single temp layer and hit summarize. – Jorge Vidinha Apr 4 '11 at 21:55

If you click statistics (in the area column of the attribute table) that was originally suggested it gives you the mean. Then simply multiply the mean by the number of polygons you have (count) and you'll get the total area (Arithmetic mean = sum of total values/ no. of values).

Actually, the code on the Statistics Geoprocessing tool help page has standalone Python code to do exactly that. It would be a simple matter of storing the outputs for later analysis. If you aren't looking to do it programmatically, you could create a model that iterates over a given list of feature classes. Then you'll simply have to aggregate the output tables.

• Found the tool. But can you be more specific about how to "create a model that iterates over a given list of feature classes" and "aggregate the output tables"? Does it require Python programming or something? Sorry I'm pretty new to this. – hpy Apr 4 '11 at 22:04
• @penuan I'm not familiar enough with model builder to give you the exact bits and bytes of it, but I would suggest taking JVIDIN's advice and doing a merge and then summarizing the output. That, at least, would not require python. There would be little benefit to feeding you code you don't understand. – Nathanus Apr 4 '11 at 22:27

Are you aware of the `arcpy.Frequency_analysis` and the `arcpy.PivotTable_management` tools? I have used these two tools in combination successfully in many of my scripts to help consolidate areas and summarize fields. These tools are also available directly from the toolbox.

If you would also like a handy script that dumps your ESRI tables to an excel spreadsheet there is a GeoPython Google Site that has a script you can download. I have used it on both 9.3 and 10.0. It has an example of how to use it in a python script. You can simply cut and paste the code then make it into a handy tool within the toolbox.