Question

I am initializing a dictionary of empty lists. Is there a more efficient method of initializing the dictionary than the following?

dictLists = {}
dictLists['xcg'] = []
dictLists['bsd'] = []
dictLists['ghf'] = []
dictLists['cda'] = []
...

Is there a way I do not have to write dictLists each time, or is this unavoidable?

Answer 1

You can use collections.defaultdict it allows you to set a factory method that returns specific values on missing keys.

a = collections.defaultdict(list)

Edit:

Here are my keys

b = ['a', 'b','c','d','e']

Now here is me using the “predefined keys”

for key in b:
    a[key].append(33)