Tuple to dictionary

Tuples: 1. Wrapped in square brackets (()), they cannot be changed (although their contents can be). Tuples can be viewed as read-only lists

A. dict.fromkeys(S)

S is a list or tuple...

Use the elements in S as the key of the dictionary. The value defaults to None. You can also specify an initial value. The code example is as follows:

myDict = dict.fromkeys('hello', True)
for k in myDict.keys():
    print(k, myDict[k])

The output is as follows:

h True

e True

l True

o True

B. collections.defaultdict([default_factory[,...]])

default_factory specifies the value type of the dictionary

>>> s = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
>>> d = defaultdict(list)
>>> for k, v in s:
...     d[k].append(v)
...
>>> d.items()
   
[('blue', [2, 4]), ('red', [1]), ('yellow', [1, 3])]

The above code is more efficient than the following Equivalent code:

>>> d = {}
>>> for k, v in s:
...     d.setdefault(k, []).append(v)
...
>>> d.items()

[('blue', [2, 4]), ('red', [1]), ('yellow', [1, 3])]

If given If default_dict is passed in int, it can be used to count:

>>> s = 'mississippi'
>>> d = defaultdict(int)
>>> for k in s:
...     d[k] += 1
...
>>> d.items()

[('i', 4), ('p', 2), ('s', 4), ('m', 1) ]