Tranpose Dict

README.md

Dictionary puzzle of the week:

The objective is to write an expression or function that, given a dictionary in which each value is a list, transpose it so the result is list of dictionaries, where:

• The keys of each new dictionary are the same as the keys of the original dictionary
• The values of the ith dictionary correspond to the ith elements of the values of the original dictionary

If that doesn't make sense, here's an example:

# Input:
d = {'a': [4, 5, 6], 'b': [7, 8, 9]}
# Expected Output:
[{'a': 4, 'b': 7}, {'a': 5, 'b': 8}, {'a': 6, 'b': 9}]

For instance, the function might have the following signature:

def transpose_dict(d: Dict[str, List[int]]) -> List[Dict[str, int]]: ...

Edge cases:

• Think about how to handle an empty dict, or values lists of length 0.
• What about if the values lists have different lengths?

transpose.py

from typing import Dict, Iterable, List


def transpose(d: Dict[str, List[int]]) -> Iterable[Dict[str, int]]:
    """
    >>> d = {'a': [4, 5, 6], 'b': [7, 8, 9]}
    >>> list(iterrows(d))
    [{'a': 4, 'b': 7}, {'a': 5, 'b': 8}, {'a': 6, 'b': 9}]
    """
    yield from (dict(zip(d.keys(), row)) for row in zip(*d.values()))