extract hex codes from layer symbology using arcpy loop

ChrisGiamarino

Hi,

I am a GIS Analyst/Urban Planner working with land use data. I have a standard land use symbology for use in different cities and counties. 

I am trying to extract the hex codes from the layer symbology and add them as a new field. The script from this solution post by @JohannesLindner . The script works to add the label of my symbology layer to a new field: 

import arcpy

layer_names = ["PW Zoning"]
aprx = arcpy.mp.ArcGISProject("current")

for name in layer_names:
    # get the layer
    layer = aprx.activeMap.listLayers(name)[0]
    # get the symbology fields and items
    renderer = layer.symbology.renderer
    fields = renderer.fields
    items = renderer.groups[0].items
    # create a dict {values: label}
    item_dict = {tuple(i.values[0]): i.label for i in items}
    # add a new field
    arcpy.management.AddField(layer, "PW_Zoning_Designation", "TEXT")
    # insert the label values
    with arcpy.da.UpdateCursor(layer, ["PW_Zoning_Designation"] + fields) as cursor:
        for row in cursor:
            key = tuple([str(x) for x in row[1:]])  # item.values stores values as string
            try:
                row[0] = item_dict[key]
                cursor.updateRow(row)
            except KeyError:  # no symbology found
                pass

I am curious how I would add the hex codes into this code to add a new field that would include the six-digit hex codes; RGB codes work too. Thanks for any help. I am new to arcpy and will be attending the Developer Conference in two months.

JohannesLindner

The original script was for Unique Values from multiple fields. You have Unique Values from one field in groups. These are represented differently in Python.

This should work:

layer_names = ["TestPolygons"]
aprx = arcpy.mp.ArcGISProject("current")

for name in layer_names:
    # get the layer
    layer = aprx.activeMap.listLayers(name)[0]
    # get the symbology fields and items
    renderer = layer.symbology.renderer
    fields = renderer.fields
    items = renderer.groups[0].items
    # create a dict {values: label}
    item_dict = dict()
    for item in items:
        for v in item.values:
            item_dict[v[0]] = item.label
    # add a new field
    arcpy.management.AddField(layer, "LandUseDesignation1", "TEXT")
    # insert the label values
    with arcpy.da.UpdateCursor(layer, ["LandUseDesignation1"] + fields) as cursor:
        for row in cursor:
            key = row[-1]
            try:
                row[0] = item_dict[key]
                cursor.updateRow(row)
            except KeyError:  # no symbology found
                pass

 

We have to change how we build the item_dict (lines 12-15) and how  to get values from it (line 21).