Creating multiple donuts with ascending hole radius (Multiple Ring Buffer)

Question

I want to use Multiple Ring Buffer (MRB) tool to create multiple donuts, but when I use NONE dissolve and outside polygon it cuts only input buffer from all created and I want it to cut first ring from the second one created. For better understanding: I create 3 buffers - 1km, 5km, 10km First is continuous from starting point and I use it as input for MRB tool. 2nd and 3rd created via MRB: 2nd is what I want because tool dissolves and is outside it. 3rd - I want to have hole with 5km radius=cuted 2nd buffer not 1st.

I know I can do it creating one after another but maybe there is way to make it in one operation? I assume that there is small (?) change of python code needed but I don't know where and how :(

• FelixIP: Aren't they donuts already?
• KaBi: Yes, they are but I want the donut hole to be larger every time. Like smaller donut cuts next/bigger one. And now they have the same size of hole.

Answer 1

I've written some python code a few years ago which creates donuts; you would wire it up to a script interface or you can hard wire the input parameters

'''
Title: Create donut rings around points
Description: Takes as input the distance of the inner and outer ring and creates a donut polygon around it.
Limitations: Tool expects units of point dataset to be in meters.
Created: 19/9/14
'''
import arcpy
import sys
# Set environment settings
arcpy.env.addOutputsToMap=True
arcpy.env.overwriteOutput = True
def main():
 try:
 # Get parameters
 layer = arcpy.GetParameterAsText(0) # Layer
 pointID = arcpy.GetParameterAsText(1) # Unique ID field
 innerBuff = float(arcpy.GetParameterAsText(2)) # Inner ring distance
 outerBuff = float(arcpy.GetParameterAsText(3)) # Outer ring distance
 outFC = arcpy.GetParameterAsText(4) # Output FeatureClass
 # Check if parameters are sensible
 if innerBuff <= 0:
 arcpy.AddWarning("The inner buffer must be greater than zero!")
 return
 if outerBuff < innerBuff:
 arcpy.AddWarning("The outer buffer must be larger than in the inner buffer value!")
 return
 features = []
 ids =[]
 # Create a cursor over the points and build donuts
 arcpy.AddMessage("Creating donuts...")
 with arcpy.da.SearchCursor(layer, ['SHAPE@', pointID]) as cursor:
 for row in cursor:
 geom = arcpy.PointGeometry(row[0].getPart(0))
 ID = row [1]
 inBuff = geom.buffer(innerBuff)
 outBuff = geom.buffer(outerBuff)
 donut = outBuff.symmetricDifference(inBuff)
 features.append(donut)
 ids.append(ID)
 # Write data to new FeatureClass
 arcpy.AddMessage("Writing features to output dataset...")
 arcpy.CopyFeatures_management(features, outFC)
 arcpy.MakeTableView_management(outFC,"tv")
 arcpy.AddField_management("tv","ID","LONG")
 x = 0
 with arcpy.da.UpdateCursor("tv",['ID']) as cursor:
 for row in cursor:
 row[0] = ids[x]
 x+=1
 cursor.updateRow(row)
 # Set output
 arcpy.SetParameterAsText(4,outFC)
 except Exception as e:
 # Report error
 arcpy.AddError(str(e))
 sys.exit("Failed to Process")
if __name__ == '__main__':
 main()

You would wire up the script as below:

Tool script properties

When you run this script it would generate output as shown below:

Example output

• KaBi: I have problem during adding this script as a tool in ArcToolbox. What should I pick as Data Type for ring distances, I've tried String, Linear Unit, Double and all have the same error comment: could not convert string to float. And is there a possibility to create multiple rings?
• Hornbydd: @KaBi I have amended my question with an image, also made a small tweak to the code for innerBuff.
• KaBi: thak you, I've skipped adding ID Field, my mistake. Once again thanks!