Python: Sorting lists of dictionaries that contain lists of other dictionaries based on length of a member in the nested dictionary

Question

An example of my data structure looks like this:

main list :

[{..}, {..}, ..] # list of dictionaries

main list stores list element dicts :

{
'queues': [{..}, {..}, ..],  # list of more dictionaries
}

inner list element dict :

{
'member': ["string", "string", ..] # list of strings
}

My goal is to sort main list based on the length of the member list in the inner dictionaries. What's an efficient and pythonic way to accomplish this?

Answer 1

You can use either sorted or list.sort with an appropriate key function. If you sort by the total length of all member lists:

main_list.sort(key=lambda d: sum(len(x['member']) for x in d['queues']))

Or if you want to always consider only the first one relevant:

main_list.sort(key=lambda d: len(d['queues'][0]['member']))