Create a sublist from list of dictionaries

Question

I want to create a sublist from current list of dictionaries base on dictionary key.

My data:

[{'0': 2}, {'0': 1}, {'1': 2}, {'2': 2}, {'2': 2}]

Data which I want to achieve:

[ [{'0': 2}, {'0': 1}], [{'1': 2}], [{'2': 2}, {'2': 2}] ]

As you can see internal arrays contain a dictionary with the same value of the key.

My code current code is like:

dicts = [{'0': 2}, {'0': 1}, {'1': 2}, {'2': 2}, {'2': 2}]

ex_list = []
sublist = []
for group in dicts:
  if group.keys() in sublist:
    sublist.append(group)
  else:
    sublist.append(group)
    if group.keys() != sublist[-1]:
      sublist = []
      sublist.append(group)
ex_list.append(sublist)

Any help highly appreciated.

Answer 1

See inline comments for explanation.

from collections import defaultdict

dicts = [{'0': 2}, {'0': 1}, {'1': 2}, {'2': 2}, {'2': 2}]

# keep track of mapping between key and values.
result = defaultdict(list)

for d in dicts:
    # d.items() returns an iterable of key/value pairs.
    # assuming each dictionary only has one key/value pair,
    # using next(iter()), we get the first pair, and pattern-match on key and val.
    key, val = next(iter(d.items())):

    # with defaultdict, if key is not present in the result dictionary,
    # the list will be created automatically.
    result[key].append(val)

# results = {0: [2,1], 1: [2], 2: [2,2]}
# for each key, values pair in results, create a list of {key: value}
# dictionaries for each value in values.

print([[{key: value} for value in values] for key, values in result.items()])

Answer 2

If you want to stay close to your program, you should keep track of the current and last key I've rewritten a little bit of your code and it got the job done.

dicts = [{'0': 2}, {'0': 1}, {'1': 2}, {'2': 2}, {'2': 2}]

ex_list = []
sublist = []
lastkey = list(dicts[0].keys())[0]

for group in dicts:
  key = list(group.keys())[0]
  if key == lastkey:
    sublist.append(group)
  else: # If key has change
    ex_list.append(sublist)
    sublist = []
    lastkey = key
    sublist.append(group)
ex_list.append(sublist) #Don't forget to include last sublist as the loop doesn't include it since no change in key

print(ex_list)