dict.fromkeys() method in Python

The fromkeys() method of dict type is used to  create a new dictionary with keys from a given iterable and values pre-filled with a specified default value.

The syntax is as shown below:

dict.fromkeys(iterable, value = None)

The items in the created dictionary has the elements from the iterable as keys and the specified value as the default value. If value is not given, None will be used.

keys = [1, 2, 3, 4, 5]

d = dict.fromkeys(keys)
print(d)

If the default value is given, the item's values will be populated with the value instead of None.

keys = ['one', 'two', 'three', 'four', 'five']

d = dict.fromkeys(keys, 0)
print(d)

In the above example, we specified 0 as the default value to the fromkeys() method.

Note that the iterable argument can be any valid iterable not just lists. In the following example we use a range() for the iterable argument.

d = dict.fromkeys(range(5))
print(d)