Count number of group layers or Layers inside group layer using ArcPy? [closed]

Question

I am looking for a way of counting the amount of layers within a group layer

I have an empty group layer inside my map and I am looking for a way of initiating a process if there are 0 layers inside the group layer. So for I have been listing layers inside layer. But if there is nothing inside .. there is nothing to loop through.

Is there a simple way to count the amount of sub layers inside a group ? For example I have a MXD with one empty group layer inside it. I want to count the amount of layers inside the group layer So far I am only able to access the layer like this

import arcpy
group = []
mxd = arcpy.mapping.MapDocument(r"C:\Users\jackw_000\Documents\mxd\layer_mapV2.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]
for lyr in arcpy.mapping.ListLayers(mxd, "my_group_layer", df):
     group.append(lyr)

print group

Returns ['My_group_layer']

When I print out the list it returns my_group_layer... . I am missing something.. ? A sub note , I am running this from IDLE , so at no time I am in seeing whats inside the TOC interface

Answer 1

I think you just need to read the esri help file on ListLayers so you understand what it is actually being returned.

This is the link. http://desktop.arcgis.com/en/desktop/latest/analyze/arcpy-mapping/listlayers.htm

In particular, note how the layers are listed and how you can use the longName property of the layers to determine which layers belong to a group (or not).

Input from Damijan

I have an empty group layer inside my map and I am looking for a way of initiating a process if there are 0 layers inside the group layer.

It appears you want to know whether a group layer is actually empty or contains layers or sub layers/groups.

Here is the code to accomplish this task:

mxd = arcpy.mapping.MapDocument("CURRENT")
df = arcpy.mapping.ListDataFrames(mxd)[0]

grpListSplit = []
grpListSplit2 = []
grpListSplitFinal = []

for grp in arcpy.mapping.ListLayers(mxd):
    # if longName contains \\ it means that it is inside the group layer
    if '\\' in grp.longName and (grp.isFeatureLayer or grp.isRasterLayer or grp.isNetworkAnalystLayer or grp.isRasterizingLayer or grp.isServiceLayer or grp.isGroupLayer):
        # make sure to obtain the first item, that is group layer name from the longName
        grpListSplit.append(grp.longName.split('\\')[0])
    # if layer does not contain \\ in longName and it is a group layer it means that it is the top group layer - you exclude the sub-group layers
    elif '\\' not in grp.longName and grp.isGroupLayer:
        grpListSplit2.append(grp2.longName)        

Taken from https://stackoverflow.com/questions/35713093/how-can-i-compare-two-lists-in-python-and-return-not-matches and slightly modified

def returnNotMatches(a, b):
    return [x for x in b if x not in a]

grpListSplitFinal = returnNotMatches( grpListSplit,grpListSplit2 )
print grpListSplitFinal

And the result:

[u'Name', u'New Group Layer']

Now do something with the grpListSplitFinal. E.g remove those empty group layers

for grp in arcpy.mapping.ListLayers(mxd):
    if grp.name in grpListSplitFinal:
        if grp.isGroupLayer:     
            arcpy.mapping.RemoveLayer(df, grp)

Both Name and New Group Layers were actually empty group layers.

Some caveats:

1. If you have more than one Group layer (an empty one and non-empty) with the same name (the main group layer not the sub-group layer) the comparison (returnNotMatches) will not work. This is because group layers name would appear in both lists. E.g. Group Layer has a name Cars and it is empty and we have another group layer with the same name containing layers and/or the sub-groups (with or without layers) then the same group layer name will appear in both lists (grpListSplit and grpListSplit2).

Possible solution:

Use something like

for i in grpListSplit:
    print i + " : " + str(grpListSplit.count(i)) 

and then apply condition based on the count.

2. If you are removing an empty Layer group and you have sub group layer with the same name under another group layer, this sub group layer will be also removed. E.g. Cars (an empty group layer) and Transport\Cars would be both removed.

Possible solution:

This could be probably solved by using indexes. Look here https://stackoverflow.com/questions/17133028/arcgis-python-index-of-layer-within-a-dataframe for the example.

3. Also code as it is will work only on the first data frame.

Solution:

Expand code that will loop through data frames

for d in arcpy.mapping.ListDataFrames(mxd):
    print d.name

Even better solution than above is to simply loop through all group layers as such:

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

cnt = 0
df = arcpy.mapping.ListDataFrames(mxd,'')[0]
listLayers = arcpy.mapping.ListLayers(mxd, '', df)
for lyr in listLayers:
   if lyr.isGroupLayer:
      for subGroup in lyr:
         cnt += 1

      if cnt == 0:
         # To rename Group layer
         lyr.name = lyr.name + "_EMPTY"
         # To delete empty Group layer
         arcpy.mapping.RemoveLayer(df, lyr)


  cnt = 0

Answer 2

To test whether a layer or group layer returned by arcpy.mapping.ListLayers() is a layer or a group layer you can use the isGroupLayer property of a Layer object:

Returns True if a layer is a group layer.

For example, to progress your code you could try changing:

for lyr in arcpy.mapping.ListLayers(mxd, "my_group_layer", df):
     group.append(lyr)

to:

for lyr in arcpy.mapping.ListLayers(mxd, "my_group_layer", df):
    if lyr.isGroupLayer:
        print lyr.name + " is a group layer"
        group.append(lyr)
    else:
        print lyr.name + " is a normal layer"