[GIS] Copying Symbology between layers with different numbers of features

arcmaparcobjectssymbologyvba

I am working on copying a layers symbology to a number of other layers which have the same geometry, table structure etc, etc but not the same number of features.

I have a state wide layer and I have written some code that selects out the different regions within the state layer based on a definition query and exports the features to shapefiles and then adds these shapefiles to ArcMap.

I am now trying to copy the symbology from the state wide layer to these other layers. However when I copy the symbology it copies the symbology that's set for the entire state.

In VBA, is there a way to remove these extra values so I end up with the same symbology as the state layer but that is specific to the layers new extent?

Best Answer

Here are two options that you can use to remove the extra State layer unique values from your exported new layer.

Trim Unique Values

Remove Unique Value Symbols out of current extent

Related Solutions

[GIS] Automatically exporting multiple maps with quantile symbology in ArcGIS Desktop

The ArcMap interface resets the symbology classification to jenks whenever you change the symbology layer, which is kind of annoying. I've gotten around this to make batches of 100s of maps using ArcPython.

First, set the symbology to run off of a field in the attribute table called "temp" or something like that. Tweak the symbology to your liking. Then you will iteratively replace that values of that field using Field Calculator, then export the map:

import arcpy

#List of names of fields to be mapped
ListOfFieldsToSymbolize = ["field1","field2","field3"]

#Temporary field that layer is currently using in ArcMap
SymbolizedField = "temp"

for Field in ListOfFieldsToSymbolize:

    #Replace temporary field with one of the fields to be mapped
    arcpy.CalculateField_management("Layer", SymbolizedField, "!" + Field + "!", "PYTHON")    

    arcpy.mapping.ExportToPDF(Current.mxd, Output.pdf)

QGIS Symbology – How to Symbolize Features with NULL Values

As @MichaelMiles-Stimson already mentioned, there doesn't seem to be a way to symbolise NULL features. However, there is an alternative whereby you create a filter to force QGIS to treat NULL values as an integer such as 0. I've included an example where I created 3 simple polygons each with a certain value:

3 polygons

Attribute table

Here is the Graduated Symbology I used with the following command:

case when "Some_Value" IS NULL then 0 else "Some_Value" end

Graduated symbology

Hope this helps!

Best Answer

Related Solutions

[GIS] Automatically exporting multiple maps with quantile symbology in ArcGIS Desktop

QGIS Symbology – How to Symbolize Features with NULL Values

Related Question