Adding a group layer to another group layer in an Mxd using python

Question

I would like to take an empty group layer and add it an existing group layer within an MXD. The empty group layer does not currently exist , i am going to use an empty group layer i have saved within a folder.

i am using a list to build the layers i would like to create and then add.

The whole process consists of having order 1 groups , that contain sub groups.

i was able to do the first step , by creating the intial layers using the code below

Group_1 = ['Scotland','England','Wales','Spain']

for first_Group in Group_1:

        mxd = arcpy.mapping.MapDocument(r"C:\GIS\PROJECT\PYTHON\GROUP_LAYER_TEMPLATE_copy.mxd")
        df = arcpy.mapping.ListDataFrames(mxd)[0]
        groupLayer = arcpy.mapping.Layer(r"C:\GIS\PROJECT\PYTHON\\An_empty_Group_Layer.lyr")
        arcpy.mapping.AddLayer(df, groupLayer, "BOTTOM")
        layers = arcpy.mapping.ListLayers(mxd)
        for layer in layers:
            if layer.isGroupLayer and layer.name == "An_empty_Group_Layer":
                layer.name = first_Group
        mxd.save()

Using the above Code , i was able to add the follwing group layers to the MXD

Scotland

England

Wales

Spain

I Like to use second list i have to create the second level of groups

 Group_2 = [['Scotland','Aberdeen'],['Scotland','Glasgow'],['Scotland','Inverness'],['England','london']['England','bristol']['England','NewCastle'],['Wales',Cardiff],['Wales','Newport']

,['Wales','Swansea'],['Spain','Mardid],['Spain','Valencia'],['Spain','Barcelonia'],

i can use a loop to go through my Second group

That would allow me to add groups , i would need to find a way using the group name to tie into adult group

# An example item in the list ['Scotland','Aberdeen']
# The first element can be used track by to the group above. In this example it would return 'Scotland'. I would like to take this value and then use it to reference the group above.

for item in group_2:
    # x equals the first element of the group 
    x = item[0]
#Can use the Second Value from the Item to be used to make the group name 
for item in group_2:
    # x Equals Aberdeen 
    x = item[1]

Another question related to group layers

Answer 1

The layers you add to your group layer has to be physically on disk or in an MXD.

To add a layer to a group layer you need to get a list of layer in your MXD. Once you have this list, you can loop through it and see if the layer is a group layer. If it is get a reference to your layer in your directory and add it to the group layer.

Sample code below assumes you already have a MXD created with your group layers and your layers are physically in a folder. I'm using a dictionary instead of a list of lists.

import arcpy
import os.path

# dict of layer to go under group layer
layers_dict = {'Scotland': ['Aberdeen', 'Glasgow', 'Inverness'],
                'England': ['London', 'Bristol', 'New Castle']}

# directory of where lyr files are located
lyr_file_dir = r'c:\gis\project\python'

mxd = arcpy.mapping.MapDocument(r'c:\gis\project\python\map.mxd')
df = arcpy.mapping.ListDataFrames(mxd)[0]
layers_list = arcpy.mapping.ListLayers(mxd)
for layer in layers_list:
    if layer.isGroupLayer and layers_dict.get(layer.name) is not None:
        for lyr in layers_dict[layer.name]:
            lyr_file = arcpy.mapping.Layer(os.path.join(lyr_file_dir, lyr) + '.lyr')
            lyr_file.name = lyr
            arcpy.mapping.AddLayerToGroup(df, layer, lyr_file, 'BOTTOM')
mxd.save()