Is there a way to show a layers feature count in the TOC?

Question

I'm using ArcGIS 10. In ArcMap's table of contents (TOC), is there a way to have the "Layer Name" automatically show a count of the total number of features in each layer?

I was thinking the TOC would look something like this:

• Roads (27)
• Streams (100)
• Parcels (12)

I found this option for Unique Value renders, but:

1. I am not an ArcObjects guy, and
2. I want to work with just the Single Value renderer.

The "List By Selection" tab sort of has this capability, but only when there are selected features.

Answer 1

As @Paul & @PolyGeo suggested, I think trying to make this a Python Add-in makes the most sense, and I will pursue that idea later.

In the meantime, I put together code that will Add/Update the TOC Name of user-defined layers in an MXD with feature counts. For my purposes, I just created this as a GP tool that would accept individual layers via a multivalue input that accepts "Layers" in the script tool. That allows me to update multiple layers "on-demand", just updating the feature counts of those layers of interest.

I haven't come up with a way to have this run automatically, however in doing some testing of old MXD's, that may not even be desirable. If you have a lot of layers with a lot of features, it could be a slow process.

import arcpy

LayerInput = arcpy.GetParameterAsText(0)

mxd = arcpy.mapping.MapDocument("CURRENT")
for lyr in arcpy.mapping.ListLayers(mxd):

    #Skip over group layers, as they have no values to count
    if lyr.isGroupLayer:
        continue

    #Determine basename of the layer, without the feature count
    name = str(lyr.name)

    #Determine if the layer is in the user-defined list
    if name not in LayerInput:
        continue

    #Determine if the layer name already includes a COUNT
    if "[" in name and "]" in name:
        lpos = name.find("[")
        basename = name[:lpos-1]
    else:
        basename = name
    print "    Updating feature count in TOC name for layer: " + str(basename)
    arcpy.AddMessage("    Updating feature count in TOC name for layer: " + str(basename) )

    # In 10.1, you may be able to use arcpy.da.SearchCursor to increase the speed.
    #http://gis.stackexchange.com/questions/30140/fastest-way-to-count-the-number-of-features-in-a-feature-class
    #fcount = 0
    #cursor = arcpy.SearchCursor(lyr)
    #for row in cursor:
    #    fcount += 1
    #del cursor

    #Get the feature count
    fcount = int(arcpy.GetCount_management(lyr).getOutput(0))

    #Update the lyr.name property
    lyr.name = basename + " [n=" + str(fcount) + "]"
    del fcount

arcpy.RefreshTOC()

#Garbage collection
del mxd