topic check for selected features in Python Questions

check for selected features

MikeLouwrens — Thu, 03 Jan 2013 17:13:25 GMT

Hi,

I trying to create an arcpy script that will run only if there are selected features in a layer, however I can't figure out how to get arcpy to test for selected features.

I've read posts about using GetCount, however this seems to only work if there is a difference in the number of selected features to the full feature count of the layer. I want my script to run even if EVERY feature in the layer is selected (but ONLY if features are selected).

Is there a way I can do this?

Cheers,
Mike.

Re: check for selected features

CarlSunderman — Thu, 03 Jan 2013 17:26:15 GMT

I would think that you could get an initial count and assign as say numRecords then run a selection and set another get count as selRecords. then check if the selected count is null

Re: check for selected features

Anonymous User — Sun, 12 Dec 2021 03:45:18 GMT

Hi,

I trying to create an arcpy script that will run only if there are selected features in a layer, however I can't figure out how to get arcpy to test for selected features.

I've read posts about using GetCount, however this seems to only work if there is a difference in the number of selected features to the full feature count of the layer. I want my script to run even if EVERY feature in the layer is selected (but ONLY if features are selected).

Is there a way I can do this?

Cheers,
Mike.

Yes, there are many ways to do this, here is one:

result = int(arcpy.GetCount_management(Parcels).getOutput(0))
if result:
    # do something
else:
    print 'No selected features'

Re: check for selected features

MikeLouwrens — Sun, 12 Dec 2021 03:45:20 GMT

Yes, there are many ways to do this, here is one:

result = int(arcpy.GetCount_management(Parcels).getOutput(0))
if result:
    # do something
else:
    print 'No selected features'

This returns a true result even if I haven't selected anything. This only returns a false result if I run a selection and nothing is selected...

Mike.

Re: check for selected features

ChrisFox3 — Thu, 03 Jan 2013 17:45:16 GMT

Layer Describe properties has an FIDSet property which returns a semicolon-delimited string of selected feature IDs. If the string is empty no features are selected:

desc = arcpy.Describe(lyr) if not desc.FIDSet  == '':    print 'Layer has a selection'

Re: check for selected features

MikeLouwrens — Sun, 12 Dec 2021 03:45:23 GMT

I would think that you could get an initial count and assign as say numRecords then run a selection and set another get count as selRecords. then check if the selected count is null

🙂

this is what I have done - I ran a selection on objectid = 1000000000000 (a feature that should never exist...) then my getcount will return 0 if nothing else selected, or the number of selected features if other features are already selected.

arcpy.SelectLayerByAttribute_management(layer.name,"ADD_TO_SELECTION",'"OBJECTID" = 1000000000000')

featurecount = int(arcpy.GetCount_management(layer.name).getOutput(0))


if featurecount > 0:
    #Do Something
else:
    arcpy.SelectLayerByAttribute_management(layer.name, "CLEAR_SELECTION")

This seems to work 😄

Cheers,
Mike.

Re: check for selected features

MikeLouwrens — Sun, 12 Dec 2021 03:45:25 GMT

Layer Describe properties has an FIDSet property which returns a semicolon-delimited string of selected feature IDs. If the string is empty no features are selected:
desc = arcpy.Describe(lyr)
if not desc.FIDSet  == '':
   print 'Layer has a selection'

oh! that works too. thanks for that 🙂

Cheers,
Mike.