Answer #1:

Use a dict comprehension:

{key: value for (key, value) in iterable}

Note: this is for Python 3.x (and 2.7 upwards). Formerly in Python 2.6 and earlier, the dict built-in could receive an iterable of key/value pairs, so you can pass it a list comprehension or generator expression. For example:

dict((key, func(key)) for key in keys)

In simple cases you don’t need a comprehension at all…

But if you already have iterable(s) of keys and/or values, just call the dict built-in directly:

1) consumed from any iterable yielding pairs of keys/vals
dict(pairs)
2) "zip'ped" from two separate iterables of keys/vals
dict(zip(list_of_keys, list_of_values))

Answer #2:

In Python 3 and Python 2.7+, dictionary comprehensions look like the below:

d = {k:v for k, v in iterable}

For Python 2.6 or earlier, see fortran’s answer.

Answer #3:

In fact, you don’t even need to iterate over the iterable if it already comprehends some kind of mapping, the dict constructor doing it graciously for you:

>>> ts = [(1, 2), (3, 4), (5, 6)]
>>> dict(ts)
{1: 2, 3: 4, 5: 6}
>>> gen = ((i, i+1) for i in range(1, 6, 2))
>>> gen
<generator object <genexpr> at 0xb7201c5c>
>>> dict(gen)
{1: 2, 3: 4, 5: 6}

Answer #4:

In Python 2.7, it goes like:

>>> list1, list2 = ['a', 'b', 'c'], [1,2,3]
>>> dict( zip( list1, list2))
{'a': 1, 'c': 3, 'b': 2}

Zip them!

Answer #5:

Create a dictionary with list comprehension in Python

I like the Python list comprehension syntax.

Can it be used to create dictionaries too? For example, by iterating
over pairs of keys and values:

mydict = {(k,v) for (k,v) in blah blah blah}

You’re looking for the phrase “dict comprehension” – it’s actually:

mydict = {k: v for k, v in iterable}

Assuming blah blah blah is an iterable of two-tuples – you’re so close. Let’s create some “blahs” like that:

blahs = [('blah0', 'blah'), ('blah1', 'blah'), ('blah2', 'blah'), ('blah3', 'blah')]

Dict comprehension syntax:

Now the syntax here is the mapping part. What makes this a dict comprehension instead of a set comprehension (which is what your pseudo-code approximates) is the colon, : like below:

mydict = {k: v for k, v in blahs}

And we see that it worked, and should retain insertion order as-of Python 3.7:

>>> mydict
{'blah0': 'blah', 'blah1': 'blah', 'blah2': 'blah', 'blah3': 'blah'}

In Python 2 and up to 3.6, order was not guaranteed:

>>> mydict
{'blah0': 'blah', 'blah1': 'blah', 'blah3': 'blah', 'blah2': 'blah'}

Adding a Filter:

All comprehensions feature a mapping component and a filtering component that you can provide with arbitrary expressions.

So you can add a filter part to the end:

>>> mydict = {k: v for k, v in blahs if not int(k[-1]) % 2}
>>> mydict
{'blah0': 'blah', 'blah2': 'blah'}

Here we are just testing for if the last character is divisible by 2 to filter out data before mapping the keys and values.

Answer #6:

Python version >= 2.7, do the below:

d = {i: True for i in [1,2,3]}

Python version < 2.7_{^{(RIP, 3 July 2010 – 31 December 2019)}}, do the below:

d = dict((i,True) for i in [1,2,3])

Answer #7:

To add onto @fortran’s answer, if you want to iterate over a list of keys key_list as well as a list of values value_list:

d = dict((key, value) for (key, value) in zip(key_list, value_list))

or

d = {(key, value) for (key, value) in zip(key_list, value_list)}

Answer #8:

Here is another example of dictionary creation using dict comprehension:

What i am tring to do here is to create a alphabet dictionary where each pair; is the english letter and its corresponding position in english alphabet

>>> import string
>>> dict1 = {value: (int(key) + 1) for key, value in
enumerate(list(string.ascii_lowercase))}
>>> dict1
{'a': 1, 'c': 3, 'b': 2, 'e': 5, 'd': 4, 'g': 7, 'f': 6, 'i': 9, 'h': 8,
'k': 11, 'j': 10, 'm': 13, 'l': 12, 'o': 15, 'n': 14, 'q': 17, 'p': 16, 's':
19, 'r': 18, 'u': 21, 't': 20, 'w': 23, 'v': 22, 'y': 25, 'x': 24, 'z': 26}
>>> 

Notice the use of enumerate here to get a list of alphabets and their indexes in the list and swapping the alphabets and indices to generate the key value pair for dictionary

Hope it gives a good idea of dictionary comp to you and encourages you to use it more often to make your code compact