Let's say I have a list a in Python whose entries conveniently map to a dictionary. Each even element represents the key to the dictionary, and the following odd element is the value
for example,
a = ['hello','world','1','2']
and I'd like to convert it to a dictionary b, where
b['hello'] = 'world'
b['1'] = '2'
What is the syntactically cleanest way to accomplish this?
b = dict(zip(a[::2], a[1::2]))
If a is large, you will probably want to do something like the following, which doesn't make any temporary lists like the above.
from itertools import izip
i = iter(a)
b = dict(izip(i, i))
In Python 3 you could also use a dict comprehension, but ironically I think the simplest way to do it will be with range() and len(), which would normally be a code smell.
b = {a[i]: a[i+1] for i in range(0, len(a), 2)}
So the iter()/izip() method is still probably the most Pythonic in Python 3, although as EOL notes in a comment, zip() is already lazy in Python 3 so you don't need izip().
i = iter(a)
b = dict(zip(i, i))
In Python 3.8 and later you can write this on one line using the "walrus" operator (:=):
b = dict(zip(i := iter(a), i))
Otherwise you'd need to use a semicolon to get it on one line.