For the tuple, `t = ((1, 'a'),(2, 'b'))`
`dict(t)` returns `{1: 'a', 2: 'b'}`

Is there a good way to get `{'a': 1, 'b': 2}` (keys and vals swapped)?

Ultimately, I want to be able to return `1` given `'a'` or `2` given `'b'`, perhaps converting to a dict is not the best way.

Try:

``````>>> t = ((1, 'a'),(2, 'b'))
>>> dict((y, x) for x, y in t)
{'a': 1, 'b': 2}
``````

A slightly simpler method:

``````>>> t = ((1, 'a'),(2, 'b'))
>>> dict(map(reversed, t))
{'a': 1, 'b': 2}
``````

Even more concise if you are on python 2.7:

``````>>> t = ((1,'a'),(2,'b'))
>>> {y:x for x,y in t}
{'a':1, 'b':2}
``````

``````>>> dict([('hi','goodbye')])
{'hi': 'goodbye'}
``````

Or:

``````>>> [ dict([i]) for i in (('CSCO', 21.14), ('CSCO', 21.14), ('CSCO', 21.14), ('CSCO', 21.14)) ]
[{'CSCO': 21.14}, {'CSCO': 21.14}, {'CSCO': 21.14}, {'CSCO': 21.14}]
``````

If there are multiple values for the same key, the following code will append those values to a list corresponding to their key,

``````d = dict()
for x,y in t:
if(d.has_key(y)):
d[y].append(x)
else:
d[y] = [x]
``````

Here are couple ways of doing it:

``````>>> t = ((1, 'a'), (2, 'b'))

>>> # using reversed function
>>> dict(reversed(i) for i in t)
{'a': 1, 'b': 2}

>>> # using slice operator
>>> dict(i[::-1] for i in t)
{'a': 1, 'b': 2}
``````