GraduatedColorsRenderer Not honoring data

NickAtEsriAU

Hi All,

I am trying to automate the addition of a polygon layer to a Map in ArcGIS Pro (2.9, 3.1) and apply a consistent symbology to the layer based an attribute (TotalCanop), which is a floating point field.  I don't want to apply symbology from a layer file as I want this code to be part of an ".atbx" with the code embedded an no other files required.

Below is the code (which is a sub part of larger script).  When it is applied to the attached shapefile only one class ("<=5.0% Canopy cover") is displayed for the layer in the table of contents.  The class that example polygon should have is "<=15.0% Canopy cover" .  In fact my preference would be to have the layer symbology show all classes in the script no matter what the range of values in the "TotalCanop" field.

Any help in fixing this would be greatly appreciated. The code I am sharing is based on help supplied by @Anonymous User to solve this post:https://community.esri.com/t5/python-questions/arcpy-update-raster-layer-symbology-using/m-p/1306854#M68119

 

import arcpy
def total_canopy_symbology(layer_filter, map_filter):
    aprx = arcpy.mp.ArcGISProject("CURRENT")
    m = aprx.listMaps(map_filter)[0]
    l = m.listLayers(layer_filter)[0]
    breaks = {0: {'upper': 5.0, 'color': [225, 225, 225, 100]},
                  1: {'upper': 10.0, 'color': [204, 204, 204, 100]},
                  2: {'upper': 15.0, 'color': [156, 156, 156, 100]},
                  3: {'upper': 20.0, 'color': [130, 130, 130, 100]},
                  4: {'upper': 30.0, 'color': [112, 168, 0, 100]},
                  5: {'upper': 100.0, 'color': [92, 137, 68, 100]}
                  }
    arcpy.AddMessage("Adding CEAs symbolised by % canopy to the Map")

    sym = l.symbology
    sym.updateRenderer('GraduatedColorsRenderer')
    sym.renderer.classificationField = "TotalCanop"
    sym.renderer.breakCount = len(breaks)
    strSta = f"Rendered applied to {l.name}\n"
    for i, brk in enumerate(sym.renderer.classBreaks):
        brk.upperBound = breaks[i]['upper']
        brk.label = "<=" + str(breaks[i]['upper']) + "% Canopy cover"
        brk.symbol.color = {'RGB': breaks[i]['color']}
        strCur = f"Adding break at {breaks[i]['upper']} with colour {breaks[i]['color']}\n"
        strSta += strCur
    l.symbology = sym
    print(strSta)
    return True
total_canopy_symbology("*CEAs", "Map")

 

 

test_CEAs.zip

Anonymous User

I don't know how this escaped me, I think I was focused on something else at the time. I think the fault is in it wont let you create more breaks/counts than features. Stepping through the code it does not set the sym.renderer.breakCount to 6 for the CEA layer so when you iterate over its list of 1 item, i is 0 and it is setting the 0 value:

brk.upperBound = breaks[i]['upper']
brk.label = "<=" + str(breaks[i]['upper']) + "% Canopy cover"
brk.symbol.color = {'RGB': breaks[i]['color']}
strCur = f"Adding break at {breaks[i]['upper']} with colour {breaks[i]['color']}\n"

The loop then stops there and that is all it does. You can test this by doing i+1 and it will show the value for 1 in the toc.

But, if ran on the other featureclasses with more than 1 feature, it seems to work ok up to the count of features. With that in mind you can change the code to get the value from the TotalCanop field and go from there, for example:

 if len(sym.renderer.classBreaks) == 1:
        value = [row[0] for row in arcpy.da.SearchCursor(l, ['TotalCanop'])][0]
        for k, v in breaks.items():
            if v['upper'] > value:
                brk = sym.renderer.classBreaks[0]
                brk.label = "<=" + str(v['upper']) + "% Canopy cover"
                brk.symbol.color = {'RGB': v['color']}
                strCur = f"Adding break at {v['upper']} with colour {v['color']}\n"
                strSta += strCur
                break

    else:
        for i, brk in enumerate(sym.renderer.classBreaks):
            brk.upperBound = breaks[i]['upper']
            brk.label = "<=" + str(breaks[i]['upper']) + "% Canopy cover"
            brk.symbol.color = {'RGB': breaks[i]['color']}
            strCur = f"Adding break at {breaks[i]['upper']} with colour {breaks[i]['color']}\n"
            strSta += strCur

gives this, with <= 15.0% for the CEAs:

You can add conditionals for featureclasses that have any feature counts below the 6 in the breaks and go from there. Hope this helps-