label polygons using arcpy

Question

I'm trying to write a python script to automate some mapping. One of the tasks I haven't figured out is how to access a layer's label properties. I'd like to set the layer's label field. I want to make an expression (something like round([length_field],2) & " m"). And I want to set the font size and font color.

Does anyone know how to do this?

Someone sent me "UpdateLayer" as a potential solution. I tried it but it doesn't seem to work with labelling. I made up a dummy .lyr file and it successfully changed the symbology of my layer. But none of the label properties I set in the .lyr file seem to have been applied to my new layer.

(edit: my subject title is actually wrong. I'm trying to label a line feature... but I don't think that's going to change the methodology of how to do this... )

RobertChappe1 · Answer

Setting False for me seems to overwrite EVERYTHING; the attributes, layer name, all of it.

It seems to have simple ran a Remove Layer and then an Add Layer rather than commuting the layer properties.

I simply want my layer to be 50% transparent and have the labels displayed with 15 point Y offset and Halo around the text.

Anyone experience this?

JoshuaChan · Answer

thanks! Yes, I've already set up everything I needed in the .lyr layerfile so setting it to "FALSE" worked.

With UpdateLayer, are you using False for the symbology_only parameter?  It defaults to True, so the label properties will only come across if you specify it as False.

For example:  arcpy.mapping.UpdateLayer(df, updateLayer, sourceLayer, False)

Keep in mind this will bring all layers properties including symbology, font, font size, label expression, etc., so everything will need to be defined in the update .lyr file.

David

DavidWatkins · Answer

With UpdateLayer, are you using False for the symbology_only parameter?  It defaults to True, so the label properties will only come across if you specify it as False.
 
For example:  arcpy.mapping.UpdateLayer(df, updateLayer, sourceLayer, False)

Keep in mind this will bring all layers properties including symbology, font, font size, label expression, etc., so everything will need to be defined in the update .lyr file.

David