Filter a dictionary of lists

Question

I have a dictionary of the form:

{"level": [1, 2, 3],
 "conf": [-1, 1, 2],
 "text": ["here", "hel", "llo"]}

I want to filter the lists to remove every item at index i where an index in the value "conf" is not >0.

So for the above dict, the output should be this:

{"level": [2, 3],
 "conf": [1, 2],
 "text": ["hel", "llo"]}

As the first value of conf was not > 0.

I have tried something like this:

new_dict = {i: [a for a in j if a >= min_conf] for i, j in my_dict.items()}

But that would work just for one key.

Answer 1

try:

from operator import itemgetter


def filter_dictionary(d):
    positive_indices = [i for i, item in enumerate(d['conf']) if item > 0]
    f = itemgetter(*positive_indices)
    return {k: list(f(v)) for k, v in d.items()}


d = {"level": [1, 2, 3], "conf": [-1, 1, 2], "text": ["-1", "hel", "llo"]}
print(filter_dictionary(d))

output:

{'level': [2, 3], 'conf': [1, 2], 'text': ['hel', 'llo']}

I tried to first see which indices of 'conf' are positive, then with itemgetter I picked those indices from values inside the dictionary.

More compact version + without temporary list using generator expression instead:

def filter_dictionary(d):
    f = itemgetter(*(i for i, item in enumerate(d['conf']) if item > 0))
    return {k: list(f(v)) for k, v in d.items()}