topic Re: SWITCH_SELECTION in SelectLayerByLocation_management in Python Questions

SWITCH_SELECTION in SelectLayerByLocation_management

GyeyoungChoi — Sat, 11 Dec 2021 22:17:57 GMT

import arcpy,sys
sdeConn = r"Database Connections\\Test.sde"
muniLoc = "Municipalities"
luLoc = "Land_Use"
tempLoc = "tempMuniLuRatio"
lu_lyr = "lu_lyr"

arcpy.env.workspace = sdeConn


try:
  print "MakeFeatureLayer_management lu_lyr"
  arcpy.MakeFeatureLayer_management(luLoc, lu_lyr) 
  prematchcount = int(arcpy.GetCount_management(lu_lyr).getOutput(0)) 
  print "MakeFeatureLayer_management muni_lyr"
  #arcpy.MakeFeatureLayer_management(muniLoc, "muni_lyr") 
  #print "SelectLayerByLocation_management NEW_SELECTION"
  #arcpy.SelectLayerByLocation_management(lu_lyr, "COMPLETELY_CONTAINS",muniLoc,"","NEW_SELECTION")
  print "SelectLayerByLocation_management SWITCH_SELECTION"
  arcpy.SelectLayerByLocation_management(lu_lyr, "COMPLETELY_CONTAINS",muniLoc,"","SWITCH_SELECTION")
  postmatchcount = int(arcpy.GetCount_management(lu_lyr).getOutput(0)) 
  if prematchcount == postmatchcount:
  print "SelectLayerByLocation_management DID NOT WORK"
  else:
  print "SelectLayerByLocation_management LOOKS GOOD"
  if arcpy.Exists(tempLoc):
  print "Delete_management "
  arcpy.Delete_management(tempLoc)
  print "CopyFeatures_management "
  arcpy.CopyFeatures_management(lu_lyr,tempLoc)
except Exception:
  e = sys.exc_info()[1]
  print(e.args[0])

Result is just same as lu_lyr even after SWICH_SELECTION option.

Where should I take a look to make this work?

Thanks,

Jack

Re: SWITCH_SELECTION in SelectLayerByLocation_management

Luis_ÁngelPascual_Camino — Tue, 27 Oct 2015 15:00:58 GMT

Hi Gyeyoung.

I've been checking the syntax on Esri help.

I see that the 4th parameter "search_distance" is optional, but is a numeric parameter. So, what I think it is doing, is assume that you don't give an optional numeric parameter, and it reads the empty string as the 5th parameter. With other words, try this:

arcpy.SelectLayerByLocation_management(lu_lyr, "COMPLETELY_CONTAINS",muniLoc,0,"SWITCH_SELECTION")

...giving zero instead of empty strig "". I think it will take it as the numeric 4th parameter, and after it will execute your switch selection.

Hope it helps. Good luck!
Luis Pascual

Re: SWITCH_SELECTION in SelectLayerByLocation_management

DarrenWiens2 — Tue, 27 Oct 2015 17:07:00 GMT

Is there a selection in your ArcMap session? It looks like you once made a selection and then commented it out.

If there is no prior selection, you are running up against a couple of quirks of GetCount and SelectLayerByLocation. 1.) GetCount returns the count of all features if there is no selection. Your variable "prematchcount" returns a count of all features because there is no selection. Later, "postmatchcount" returns a count of all features, because all features are selected. 2.) When you use "SWITCH_SELECTION", the second and third parameters are ignored, so there is no spatial component to the tool whatsoever at that point.

Re: SWITCH_SELECTION in SelectLayerByLocation_management

NeilAyres — Tue, 27 Oct 2015 17:10:27 GMT

And there is a whole bunch of indentations after the ifs that need to be sorted out.

Re: SWITCH_SELECTION in SelectLayerByLocation_management

curtvprice — Sat, 31 Oct 2015 04:31:51 GMT

Darren is right on with SWITCH_SELECTION. Maybe you really meant "REMOVE_FROM_SELECTION"?

To avoid confusion, I always use SWITCH_SELECTION in my code with SelectLayerByAttribute (simpler syntax):

arcpy.SelectLayerByAttribute(lyr, "SWITCH_SELECTION")