Building from How do I create a dictionary with keys from a list and values defaulting to (say) zero? and especially this answer:
How do I create a dictionary with keys from a list and values separate empty lists?
(Where, later on, I'll be able to append elements)
Use dictionary comprehension,
{item: [] for item in my_list}
You are simply iterating the list and creating a new list for every key.
Alternatively, you can think about using collections.defaultdict, like this
from collections import defaultdict
d = defaultdict(list)
for item in my_list:
d[item].append(whatever_value)
Here, the function object which we pass to defaultdict is the main thing. It will be called to get a value if the key doesn't exist in the dictionary.
This is simple and easy implementation , It is self explaining , we iterate over all the elements in the list and create a unique entry in the dictionary for each value and initialize it with an empty list
sample_list = [2,5,4,6,7]
sample_dict = {}
for i in sample_list:
sample_dict[i] = []
By normal method:
>>> l = ["a", "b", "c"]
>>> d = {}
>>> for i in l:
... d[i] = []
...
>>> d
{'a': [], 'c': [], 'b': []}
>>>
By using collections module
>>> l = ["a", "b", "c"]
>>> import collections
>>> d = collections.defaultdict(list)
>>> for i in l:
... d[i]
...
[]
[]
[]
>>> d
defaultdict(<type 'list'>, {'a': [], 'c': [], 'b': []})
