Converting list to dictionary with list elements as index - Python

Question

From Python: create dict from list and auto-gen/increment the keys (list is the actual key values)?, it's possible to create a dict from a list using enumerate to generate tuples made up of incremental keys and elements in life, i.e.:

>>> x = ['a', 'b', 'c']
>>> list(enumerate(x))
[(0, 'a'), (1, 'b'), (2, 'c')]
>>> dict(enumerate(x))
{0: 'a', 1: 'b', 2: 'c'}

It is also possible to reverse the key-value by iterating through every key in the dict (assuming that there is a one-to-one mapping between key-value pairs:

>>> x = ['a', 'b', 'c']
>>> d = dict(enumerate(x))
>>> {v:k for k,v in d.items()}
{'a': 0, 'c': 2, 'b': 1}

Given the input list ['a', 'b', 'c'], how can achieve the dictionary where the elements as the key and incremental index as values without trying to loop an additional time to reverse the dictionary?

Thanks! I'm sooo blind at the last hour of work on a friday. hahahaa... — alvas, Oct 07 '16 at 10:16
Does this answer your question? [Python: Convert list to dictionary with indexes as values](https://stackoverflow.com/questions/36459969/python-convert-list-to-dictionary-with-indexes-as-values) — Tomerikoo, Dec 02 '21 at 13:12

score 3 · Accepted Answer · answered Oct 07 '16 at 10:10

3

How about simply:

>>> x = ['a', 'b', 'c']
>>> {j:i for i,j in enumerate(x)}
{'a': 0, 'c': 2, 'b': 1}

answered Oct 07 '16 at 10:10

alvas

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Dictionary comprehension!? – CraigDavid May 25 '20 at 01:18

Converting list to dictionary with list elements as index - Python

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