# Extracting values using buffers, equation and ArcMap

I have run a linear regression and obtained an equation that describes the link between a group size and the area used by this group. Now, I would like to enter this equation into the GIS to obtain buffers of different sizes depending on the group size. For instance, a group of 50 individuals may end up with a buffer of 100m diameter. I was going to add a field in the attribute table "buffer" and enter the equation.

After that, I was wondering if I could use my different buffers to extract values from rasters in a simple way?

I mean that I would like to extract the average value but based on my buffer size and without having to make a hundred shapes.

• What version of ArcMap are you using? Also, you can base the Buffer tool off of values in the attribute table so that each feature will have it's own buffer radius. Does that help any?
– Paul
Jun 29, 2013 at 22:00
• What is the connection between a "group" and location? Jun 30, 2013 at 13:32
• I am using ArcMap 10. I already have a buffer value for each point but I am having issues to extract raster data from those buffers. I have tried Zonal stats, GME and everything crashes :( Jul 2, 2013 at 23:22

## 1 Answer

You can calculate the pixel values within polygon zones by using either Zonal Statistics or Zonal Statistics as Table. Alternatively, consider using isectpolyrst (Intersect Polygons With Raster) in GME, which has both R and ArcGIS dependencies.

• Thank you so much for your help. Unfortunately when I use GME, some of my polygons are not attributed a logical value (e.g. -1.70000). Those problem points are random and I do not understand where the problem is. Zonal statistics is not working properly either. My buffers were created dissolved so it should not be because they overlap, but I have 2770 points and I get only 900 results if I extract values from a DEM with Zonal statistics as Table. Could it be because some buffers have a radius inferior to 30m and my rasters' cells are 30x30? Jul 2, 2013 at 15:23
• @ElenaSpark I think you should revise your original question using the edit button to reflect what you have learned from the assistance that Aaron has given so far.
– PolyGeo
Jul 17, 2013 at 0:55
• @ElenaSpark I suspect you are getting 900 results rather than ~2770 because you used the dissolve command on the buffers. Unfortunately, I cannot troubleshoot your dataset very well because I do not have a clear understanding of your workflow.
– Aaron
Jul 17, 2013 at 3:07