topic Re: How to set the symbology categories using arcpy in Python Snippets Questions

How to set the symbology categories using arcpy

PeterBirksmith — Tue, 17 May 2016 03:26:12 GMT

Hi there

I would like to learn how to modify/add categories within Symbology programmatically in arcpy.

I have created a Featurelayer from a shapefile. Now I want to set the available categories

Is this possible and if so what is the code necessary to perform this function.

Cheers

Peter

Re: How to set the symbology categories using arcpy

DanPatterson_Retired — Tue, 17 May 2016 05:12:20 GMT

see arcpy.mapping ... for example

EDIT the direct links didn't work so I will give references to the actual classes

in the arcpy mapping classes section Introduction to arcpy.mapping—Help | ArcGIS for Desktop

UniqueValuesSymbology

GraduatedColorsSymbology

GraduatedSymbolsSymbology

The code samples will get you started

Re: How to set the symbology categories using arcpy

PeterBirksmith — Tue, 17 May 2016 23:09:10 GMT

Hi Dan

Seems that I can't get the links to work but you've given me the functions I need to use so that's the important point

Cheers

Peter

Re: How to set the symbology categories using arcpy

DanPatterson_Retired — Tue, 17 May 2016 23:33:52 GMT

Yes Peter, sometimes this happens and I still can't get them to work, but they are in the arcpy.mapping section under Classes

Re: How to set the symbology categories using arcpy

PeterBirksmith — Wed, 18 May 2016 01:00:18 GMT

Hi Dan

Thanks again

I've tried the snippet of code however, I think I need to understand a bit more about symbologyType and where it captures this attribute from within an mxd.

would you mind if I provided you the mxd as it's created from BOM shapefiles which produces the layers.

When I run the code SymbologyType comes back as 'OTHER'

I'm obviously missing something.

print lyr.symbologyType

Returns 'OTHER'

if lyr.symbologyType == "UNIQUE_VALUES": lyr.symbology.valueField = "SUB_REGION" lyr.symbology.addAllValues() arcpy.RefreshActiveView() arcpy.RefreshTOC()

Cheers

Peter

Re: How to set the symbology categories using arcpy

DanPatterson_Retired — Wed, 18 May 2016 01:40:01 GMT

well OTHER means .... A string that represents an unsupported layer symbology class.

So what is your symbology class, there is only the list in the layer class

What is the layer? a featureclass?

You are running it from the current project as follows

import arcpy

mxd = arcpy.mapping.MapDocument("current") # run from within a currently open project

lyr = arcpy.mapping.ListLayers(mxd, "Population")[0] # this is a layer(s) called Population within the project [0] means get the 1st

if lyr.symbologyType == "UNIQUE_VALUES": # it then checks to see if this is the symbology type

lyr.symbology.valueField = "SUB_REGION" # if it is, use a specific field in the layer's table

etc etc etc