List of dicts to/from dict of lists

Question

I am looking to change back and forth between a dictionary of lists (all of the same length):

DL = {'a': [0, 1], 'b': [2, 3]} 

and a list of dictionaries:

LD = [{'a': 0, 'b': 2}, {'a': 1, 'b': 3}] 

I am looking for the cleanest way to switch between the two forms.

Answer 1

For those of you that enjoy clever/hacky one-liners.

Here is DL to LD:

v = [dict(zip(DL,t)) for t in zip(*DL.values())] print(v) 

and LD to DL:

v = {k: [dic[k] for dic in LD] for k in LD[0]} print(v) 

LD to DL is a little hackier since you are assuming that the keys are the same in each dict. Also, please note that I do not condone the use of such code in any kind of real system.

Answer 2

If you're allowed to use outside packages, Pandas works great for this:

import pandas as pd pd.DataFrame(DL).to_dict(orient="records") 

Which outputs:

[{'a': 0, 'b': 2}, {'a': 1, 'b': 3}] 

You can also use orient="list" to get back the original structure

{'a': [0, 1], 'b': [2, 3]}