One liner: creating a dictionary from list with indices as keys

I want to create a dictionary out of a given list, in just one line. The keys of the dictionary will be indices, and values will be the elements of the list. Something like this:

a = [51,27,13,56]         #given list

d = one-line-statement    #one line statement to create dictionary

print(d)

Output:

{0:51, 1:27, 2:13, 3:56}

I don’t have any specific requirements as to why I want one line. I’m just exploring python, and wondering if that is possible.

Answers:

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Method 1

a = [51,27,13,56]
b = dict(enumerate(a))
print(b)

will produce

{0: 51, 1: 27, 2: 13, 3: 56}

enumerate(sequence, start=0)

Return an enumerate object. sequence must be a sequence, an iterator, or some other object which supports iteration. The next() method of the iterator returned by enumerate() returns a tuple containing a count (from start which defaults to 0) and the values obtained from iterating over sequence:

Method 2

With another constructor, you have

a = [51,27,13,56]         #given list
d={i:x for i,x in enumerate(a)}
print(d)

Method 3

{x:a[x] for x in range(len(a))}

Method 4

Try enumerate: it will return a list (or iterator) of tuples (i, a[i]), from which you can build a dict:

a = [51,27,13,56]  
b = dict(enumerate(a))
print b

Method 5

Simply use list comprehension.

a = [51,27,13,56]  
b = dict( [ (i,a[i]) for i in range(len(a)) ] )
print b

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0