Cannot update layer symbology

curtvprice — Sat, 11 Dec 2021 06:34:21 GMT

I am trying to follow the example in the help for Layer:

import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Census")[0]
lyr = arcpy.mapping.ListLayers(mxd, "StatePopulation", df)[0]
lyrFile = arcpy.mapping.Layer(r"C:\Project\LYRs\Population.lyr")
arcpy.mapping.UpdateLayer(df, lyr, lyrFile, True)
if lyr.symbologyType == "GRADUATED_COLORS":
  lyr.symbology.valueField = "POP2000"
  lyr.symbology.numClasses = 4
  lyr.symbology.classBreakValues = [250000, 999999, 4999999, 9999999, 35000000]
  lyr.symbology.classBreakLabels = ["250,000 to 999,999", "1,000,000 to 4,999,999", 
                                    "5,000,000 to 9,999,999", "10,000,000 to 35,000,000"]

Here is my pathetic dialog with the Python window...

>>> mxd = am.MapDocument("current")
>>> df = am.ListDataFrames(mxd, "ValueMap")[0]
>>> df.name
u'ValueMap'
>>> lyr = am.ListLayers(mxd, "County*", df)[0]
>>> lyr.name
u'County Data'
>>> am.UpdateLayer(df, lyr, am.Layer("q.lyr"), True)
>>> lyr.symbology.valueField 
u'AQ_WGWTo.AQ_WGWTo_2010'
>>> lyr.symbologyType
u'GRADUATED_COLORS'
>>> lyr.symbology.numClasses = 5
Runtime error 
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "c:\arcgis\desktop10.2\arcpy\arcpy\arcobjects\_base.py", line 89, in _set
    return setattr(self._arc_object, attr_name, cval(val))
RuntimeError
>>> # however this works - and displays immediately in the map (with unchanged symbology)
>>> lyr.symbology.valueField = u'AQ_WGWTo.AQ_WGWTo_2000'
>>> # and this generates no error but does not change the break values as promised
>>> lyr.symbology.reclassify()

Any ideas what I'm doing wrong????

Re: Cannot update layer symbology

curtvprice — Fri, 20 Jun 2014 21:30:18 GMT

Sorry to bother everyone. When I copy the data to the table and remove the active join from the layer, everything works as advertised. So, don't use the reclassify method does not work for me if there a join on the layer.

I reproduced this problem with 10.1 SP 1 and 10.2.2. Argh.

topic Cannot update layer symbology in Mapping Questions

Cannot update layer symbology

Re: Cannot update layer symbology