topic Re: Select By Attribute with Variable in Python Questions

Select By Attribute with Variable

ebrown — Sun, 02 May 2021 21:46:55 GMT

I'm trying to iterate through a shapefile with all of the roads in the State of Maine, select only the roads in towns relevant to my project, and then create one new feature class with just those roads. I'm working in Python in a Jupyter notebook and I'm a beginner in both Python and ArcGIS. This code runs, but selects all of the roads, not just those in the town list.

# Create town list town_list = ['Bangor','Hampden','Veazie','Orono','Brewer','Old Town'] arcpy.env.overwriteOutput = True for town in town_list: select = """TOWN = '{}'""".format(town) arcpy.SelectLayerByAttribute_management(ME_roads,'NEW_SELECTION',select) arcpy.CopyFeatures_management(ME_roads,relevant_roads)

Re: Select By Attribute with Variable

DavidPike — Sun, 02 May 2021 23:16:08 GMT

I'd say there's a few too many quotes in select:

select = "TOWN = '{}'".format(town)

Have you also made it a feature layer to run it on?

Re: Select By Attribute with Variable

DanPatterson — Mon, 03 May 2021 01:39:30 GMT

Of course you could always just use

Split By Attributes (Analysis)—ArcGIS Pro | Documentation

Re: Select By Attribute with Variable

JoeBorgione — Mon, 03 May 2021 14:20:39 GMT

From another set of eyes; I like f strings over the format() function if you are using Python 3.x:

select = f'TOWN = {town}'

I too wondered what @DavidPike mentioned about a feature layer...