# How do I split a large number of polygons at the same time into smaller polygons.

I would like to split the large polygons in the picture below into smaller polygons using the border. I have about 4000 lots that I would like to divide and find the area of each of the smaller sections of the polygons but every process I have used so far will not allow me to work on more then one polygon at a time.

I am a student that does not have much experience with Python but can try it out. Please advise, thanks.

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More details may help us to better answer your question. Are the polygons and border both shapefiles? What version of ArcGIS are you running? Once you have the polygons chopped up, do you want to calculate area using regular units (i.e., acres, square meters, etc.)? Etc. –  Baltok Apr 25 '12 at 19:21
They are both shapefiles, one is a line and the other is a polygon. I am running ArcGIS 10.0. The ultimate goal is to calculate the area of the "chopped" up polygons in square meters. Thanks, Adam –  Adam Apr 25 '12 at 19:43
Additionally Split does not seem to work for some reason it does not recognize the line shapefile as the feature to "split" the polygon shapefile –  Adam Apr 25 '12 at 19:51

Think you probably need Split (in the Analysis Toolbox).

You shouldn't need Python - this is a fairly standard GIS task. ESRI don't half make things difficult to find though!

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Note: Split is only available to people with ArcInfo level licensing –  GIS-Jonathan Apr 26 '12 at 11:33

You can make a polygon feature class with the border polylines using FeatureToPolygon, and then get the intersection of the two polygon layers with Intersect. The intersection class must contain the splited polygons.

Hope this helps.

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I have tried intersect as well but the system keep giving me error 999999 - invalid topology. Any further advice? Thanks. –  Adam Apr 25 '12 at 21:25
Check this thread: <forums.esri.com/Thread.asp?c=93&f=983&t=222076>;. Maybe changin the enviroment settings disabling the M values (or/and Z values) is the solution. –  cag Apr 26 '12 at 4:48

Based on your description, you might look into the Split Polygons tool on the Topology toolbar. This allows you to use a line/polygon shapefile to chop up a polygon shapefile. You will need an ArcInfo license to run it. Also, be forewarned that if you are attempting to chop up lots of polygons with many vertices, it could take awhile to process or could hang/crash depending on your computer's hardware.

An alternative would be to use Feature to Polygon to convert the border/lines shapefile to polygons, and then Intersect with the other polygons layer to chop it up. Feature to Polygon does require an ArcInfo license. An alternative to Feature to Polygon is to install the ET GeoWizards Toolbar which has a Polylines to Polygons tool which does the same thing and is free and doesn't require an ArcInfo license.

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I do have ArcInfo but I must not have the full license because I do have the split polygons tool. –  Adam Apr 25 '12 at 21:21
I have tried to use the second method you described but Intersect does not work - I keep getting an error 999999 - invalid topology and it fails to execute. Thanks so much for all your help by the way. –  Adam Apr 25 '12 at 21:22
Split Polygons is not a tool you can search for in ArcToolbox; it is only a button found on the Topology toolbar. If you turn on the Topology toolbar, it should be the sixth button from the right. Regarding Intersect not working, the most likely culprit is that when you converted your lines to polygons with Feature to Polygon, it introduced topology errors. You might look through your converted polygon shapefile to see if there are some obvious errors. The Topology toolbar has some other tools to help check your layer for topology errors. It might be worth reading through ESRI's help. –  Baltok Apr 25 '12 at 22:10