Divide shp in about 20-50 adjacent polygons?

JohannesBierer — Fri, 10 Dec 2021 22:25:28 GMT

I would like to divide a shp in about 20-50 adjacent polygons. I have the following script but the while loop (line 54) becomes endless if there are less than 10 adjacent polygons to select. Any ideas for a better solution?

# -*- coding: cp1252 -*-

import arcpy

arcpy.env.overwriteOutput = True

arcpy.env.workspace = "in_memory"

Alk_Sel = r"R:\Daten\sgb_Planungen\2013\Saalbachniederung\Eigentuemer\ALK_merge_E.shp"
alk_sel_Layer = "alk_sel_Layer"
InFile = r"C:\temp2\InFile.shp"

def SicFeature():
    
    arcpy.CopyFeatures_management(Alk_Sel, InFile)
    arcpy.MakeFeatureLayer_management(InFile, alk_sel_Layer)

def AddField():

    arcpy.AddField_management(alk_sel_Layer, "Round", "LONG")

def selectMin():

    sum = arcpy.GetCount_management(alk_sel_Layer)
    print sum

    i = 0

    for i in range(1, int(sum.getOutput(0)), 10):

        i += 1
    
        Expression = """ "Round" = {} """.format(0)
        
        arcpy.MakeFeatureLayer_management(InFile, alk_sel_Layer, Expression )
        
        sum1 = arcpy.GetCount_management(alk_sel_Layer)
        print('{} has a sum of {} records'.format(alk_sel_Layer, sum1[0]))

        MyList = list()
        cursor = arcpy.da.SearchCursor(alk_sel_Layer, "FID")

        for row in cursor:
            MyList.append(int(row[0]))

        print 'Minimum: {0}'.format(min(MyList))

        expression1 = min(MyList)

        arcpy.SelectLayerByAttribute_management(alk_sel_Layer, "NEW_SELECTION", """ "FID" = {} """.format(expression1))
        
        result1 = arcpy.GetCount_management(alk_sel_Layer)
                    
        while (int(result1.getOutput(0)) < 10):
          
            arcpy.SelectLayerByLocation_management (alk_sel_Layer, "INTERSECT", alk_sel_Layer)

            result1 = arcpy.GetCount_management(alk_sel_Layer)
            print(result1)

        arcpy.CalculateField_management(alk_sel_Layer, "Round", i)

        OutFile = r"C:\temp2\OutFile_{}.shp".format(i)
        arcpy.CopyFeatures_management(alk_sel_Layer, OutFile)

SicFeature()
AddField()
selectMin()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Divide shp in about 20-50 adjacent polygons?

NeilAyres — Wed, 09 Oct 2019 09:09:01 GMT

You generate a list of "i" in line 29, then in 31 you increment "i".

Then you only seem to use the value of "i" inside the while loop to identify the output.

Consider using 2 separate counters so you don't get confused and increment inside the while loop.

Re: Divide shp in about 20-50 adjacent polygons?

JohannesBierer — Wed, 09 Oct 2019 12:46:36 GMT

Thank you,

remains the question how to get out of the while loop if the result1 value didn't change.

Re: Divide shp in about 20-50 adjacent polygons?

JohannesBierer — Fri, 10 Dec 2021 22:25:30 GMT

while (int(result1.getOutput(0)) < 10):

            old_value = int(result1.getOutput(0))
            
            arcpy.SelectLayerByLocation_management (alk_sel_Layer, "INTERSECT", alk_sel_Layer)

            result1 = arcpy.GetCount_management(alk_sel_Layer)
            print(result1)

            if int(result1.getOutput(0)) == old_value:
                break‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

This was the solution for me.

topic Re: Divide shp in about 20-50 adjacent polygons? in Python Questions

Divide shp in about 20-50 adjacent polygons?

Re: Divide shp in about 20-50 adjacent polygons?

Re: Divide shp in about 20-50 adjacent polygons?

Re: Divide shp in about 20-50 adjacent polygons?