I want to interchange keys and value in a given dictionary. For example:
dict = {1:'sandeep', 2: 'suresh', 3: 'pankaj'}
will become:
dict1 = {'sandeep': 1, 'suresh': 2, 'pankaj': 3}
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jonrsharpe
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Sandeep Upadhyay
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`{val: key for key, val in dict.items()}`? But you shouldn't name your own dictionary `dict`, and will you **always** have unique, hashable values? – jonrsharpe Apr 07 '15 at 10:32
2 Answers
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Using zip is probably better than a dictionary comprehension:
dict1 = dict(zip(dict1.values(), dict1.keys())) # better for beginners
Malik Brahimi
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1Make sure your original dictionary is `dict1` instead of `dict`. – Malik Brahimi Apr 07 '15 at 10:43
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Beginners aren't too familiar with comprehensions in general, but most are familiar with some of the built-in methods. – Malik Brahimi Apr 07 '15 at 11:18
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I don't think you should make that assumption. And even if true, beginners ought to become familiar with them. – MJeffryes Apr 07 '15 at 11:32
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In [45]: d = {1:'sandeep',2 : 'suresh', 3: 'pankaj'}
In [46]: {(v, k) for k,v in d.iteritems()}
Out[46]: {'pankaj': 3, 'sandeep': 1, 'suresh': 2}
Note the use of d as the variable name instead of the built-in dict.
Also note that you are not guaranteed uniqueness and can loose entries:
In [47]: d = {1:'sandeep',2 : 'suresh', 3: 'pankaj', 4:'suresh'}
In [48]: {(v, k) for k,v in d.iteritems()}
Out[48]: {'pankaj': 3, 'sandeep': 1, 'suresh': 4}
Mike Bessonov
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1Why aren't you using a dictionary comprehension directly? `{v: k for k,v in d.iteritems()}` – MJeffryes Apr 07 '15 at 11:00
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@MJeffryes Yes, you are right, much better this way. Edited the answer accordingly. – Mike Bessonov Apr 07 '15 at 11:04
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1According to the tag "**python-3.x**" `iteritems` should be replaced by `items`. – Matthias Apr 07 '15 at 11:33