How to convert the dictionary containing keys and list of list value?

Question

• How to convert the dictionary containing keys and list of list values to dictionary containing keys and list, drop duplicated in the newly created list ?
• I tried running the following function and the computer got an 'memory error'

from collections import defaultdict

my_dict = defaultdict(list)    
for k, v in zip(df_Group.guest_group, df_Group.list_guest):
  for item in v:
    v.append(item)    
  my_dict[k].append(set(v))

• My origin dictionary created from 2 columns of one dataframe like: {Group1: [[1,2,3,4], [1, 2, 5, 6 ]]}
• I want my dictionary like : {Group1: [1,2,3,4,5,6]}

Answer 1

From what I understood, what you essentially want to do is flatten your list while keeping unique items. The unique items can be achieved by converting the list into set and then back to list. The unpacking part is really well explained in this post. Here's a working code for you -

df_dict = {
    'Group1': [[1,2,3,4], [1, 2, 5, 6 ]],
    'Group2': [[1,2], [2,3],[2,3,4]]
}

final_dict = {}

for k, v in df_dict.items():
    # flatten the list using double list comprehension
    flat_list = [item for sublist in v for item in sublist]
    final_dict[k] = list(set(flat_list))

This gives the final_dict as -

{'Group1': [1, 2, 3, 4, 5, 6], 'Group2': [1, 2, 3, 4]}

Please tell me if this answers your query.

Edit for Integer values in between the lists - If we have a list with integer values in between, then you will get the int object not iterable error, to solve it we can check the instance to be int and make the item list by ourselves

Working code -

df_dict = {
    'Group1': [[1,2,3,4], 3, [1, 2, 5, 6 ]],
    'Group2': [[1,2], [2,3],[2,3,4]],
}

final_dict = {}

for k, v in df_dict.items():
    # making a new list 
    new_list = []
    for item in v:
        # for int we will convert it to 1 length list
        if isinstance(item, int):
            item = [item]
        for ele in item:
            new_list.append(ele)
    final_dict[k] = list(set(new_list))

final_dict

Final dict -

{'Group1': [1, 2, 3, 4, 5, 6], 'Group2': [1, 2, 3, 4]}

As expected