Arcpy apply symbology from layer

Question

I have some substances TPH, CO2, SO2, VOC, analyzed in a period of time 2001 - 2017. In the .mxd each year is a group layer, containing all the substances for that year:

2001: - TPH

  - CO2

  - SO2

  - VOC

2002 - TPH

  - CO2

  - SO2

  - VOC

...until 2017

I want to apply the same symbology for TPH substance in 2001, 2002, 2003 etc. I have made .lyr files for all the substances, but I have managed to write a functional code to apply one symbology for all layers in the same group layer.

Any solution to apply the same symbology for just one layer in all the group layers?

I have many more substances than the ones mentioned!

import arcpy

mxd = arcpy.mapping.MapDocument("CURRENT")

df = mxd.activeDataFrame

groupName = "2001"

allLayers = arcpy.mapping.ListLayers(mxd, groupName, df) [0]

for layer in allLayers: 

    arcpy.ApplySymbologyFromLayer_management(layer, "TPH")

PS: I use ArcMap 10.6 and the batch function for the Apply Symbology From Layer tool is not working

Answer 1

Apply your symbols to all layers in one Group (named template_group below) then try code below. It will match by layer name and apply the same symbology as the layers in the template Group:

import arcpy

template_group = '2001' #Change to match your group with the symbolized layers
mxd = arcpy.mapping.MapDocument("CURRENT")
df = mxd.activeDataFrame
template_layers = {l.name:l for l in arcpy.mapping.ListLayers(arcpy.mapping.ListLayers(mxd,template_group)[0]) if not l.isGroupLayer} #Create a Dictionary of layer name as key and layer as value

other_groups = [g for g in arcpy.mapping.ListLayers(mxd) if (g.isGroupLayer and g.name!=template_group)]

for group in other_groups:
    layers = [l for l in arcpy.mapping.ListLayers(arcpy.mapping.ListLayers(mxd,group)[0]) if not l.isGroupLayer]
    for lyr in layers:
        if lyr.name in template_layers:
            arcpy.ApplySymbologyFromLayer_management(in_layer=lyr, 
                                                    in_symbology_layer=template_layers[lyr.name])