# Ratio of area between park and residential parcels

I have three shapefiles: park, residential parcel, and participants of a survey (single Point shapefile with 100 dots).

I want to find a ratio of area (park/residential parcel) within 1 and 0.5 mile buffer of the applicants. I have total applicants of about 100.

What are the steps that I need to follow to perform this work in ArcMap?

So far I created 1 and 0.5 mile buffer around the applicants and clipped the park area and parcel areas with the buffer shapefile.

What should I do next so that I can find the ratio of area used by each applicants?

I am using ArcMap 10.2.2. Is it possible through ArcMap?

In the figure, two red dots are my applicants, the blue colored polygons are clipped parks within 1 mile buffer of those two applicants, and light apple green color is parcels clipped within those buffer. Now i need a ratio of area between those blue color to light apple green color within each buffer.

• I'm a little unclear regarding the "ratio of area used". Do you want to calculate the area intersected by the buffer and the park(s)? Commented Jan 13, 2016 at 21:15
• Well basically it sounds like you say jbchurchill, but buffer covers the area of the streets whereas parcels does not, that's the reason i want to find the ratio between park and parcel area within the buffer.
– Lira
Commented Jan 13, 2016 at 21:21
• I'm also confused as to what you're trying to achieve. Could you add a simple diagram which explains the desired outcome? Commented Jan 13, 2016 at 21:55

If you have an advanced licence, there is a tool called tabulate intersection that does just what you need (ESRI snapshot below). Otherwise, use @jbchurchill's method.

• Very good suggestion. I think @Lira will still need to do the concatenation steps 3 and 5 in my answer in order to get the final result. I was unaware of this tool which would simplify my answer from 2 geoprocessing tools into 1 (duly noted!). Commented Jan 14, 2016 at 15:18

I wanted to test my method to be sure it would work. I digitized 2 overlapping circles (similar to what you show in the question).

Then I ran an INTERSECT Operation (Geoprocessing Menu or Analysis Tools->Overlay->Intersect in the toolbox) using a zoning layer. The small circle (FID = 0) is entirely in one zone but the larger one (FID = 1) is split into 2 zones (like parks and parcels for example). Then I updated the area by right-clicking the Shape_Area field and using "Calculate Geometry". Then I needed a summary of area by FLU (park or parcels) and FID from the buffers. For this I added a field and calculated it to a concatenation of FLU and FID_TES_O and ran summary statistics. I'll break this down into steps (below the table graphic):

1) Be sure parks and parcels are in the same layer (merge if necessary). There should be a field that identifies parks and a field that identifies parcels (non-park).
2) Run the Intersect Tool on the combined Park & Parcel Layer. Note that @radouxju 's answer below might be used as an alternative here to skip my step 6
3) Add a field (see graphic below) called SUMFIELD and make it text.
4) Update the geometry field for corrected area (or add a field for this).
5) Calculate the SUMFIELD as follows [FLU] & "_" & [FID_TEST_O]
note the resulting graphic below showing table result.
replace FLU with whatever field you use for Parks vs. Parcels. 6) Now right-click the SUMFIELD field and choose Summarize.
7) As shown in the last graphic below, Check the box to SUM by the SUMFIELD. The resulting table will give you the calculated area for each category (park or parcel) for each FID.
8) The last step will be to calculate the ratio of park to parcel for each FID. If you isolate the records that match the numbers after the underscore "_" (you can just do a selection for each participant FID and calculate the values from that).

So, if I'm getting right, you are looking for a ratio, means a single number, which comes from park area/residential area. For that you need to get the area of each shapefiles. You can use the following tool:

http://desktop.arcgis.com/en/desktop/latest/tools/spatial-statistics-toolbox/calculate-areas.htm

This creates an additional field with the area size for each polygon. Now you either just add these number together and get the whole residential/park area within the buffer or you can start the whole process by merging them together. When you have both the park and residential area, you can easily calculate the ratio.

PS. If you have to make this like 100 times, you should consider to use model builder or python script to fasten it up