How to transpose a dictionary in python, reverse mapping?

Asked Apr 08 '17 at 16:01

Active Apr 08 '17 at 16:46

Viewed 2,040 times

I have a dictionary in python which is like below.

{'abc': [1,2,3], 'def': [2,3,4], 'gh': [3,4]}

I want to convert it to another dictionary like this:

{
1: 'abc',
2: 'abc, def',
3: 'abc, def, gh',
4: 'def, gh'
}

I wrote the following code, but got an error. How do I concatenate the values in dictionary? The order doesn't matter. thanks

old_dict=dict({'abc': [1,2,3], 'def': [2,3,4], 'gh': [3,4]})

new_dict1=dict()
for k, vlist in old_dict.items():
    for v in vlist:
        new_dict1[v]=new_dict1[v] + ", " + k

Traceback (most recent call last):
  File "<console>", line 3, in <module>
KeyError: 1

edited Apr 08 '17 at 16:46

asked Apr 08 '17 at 16:01

teapot

1

Can you give us a clue by showing your code? – Mazdak Apr 08 '17 at 16:03
Dictionaries are not ordered; you can't expect a specific order of the joined string keys in the output. It's otherwise perfectly doable, just invert the dictionary, then join the resulting value sequences into one string. – Martijn Pieters Apr 08 '17 at 16:04
Actually not a dupe, because this one has list items as value in the map(dict)?! – officialaimm Apr 08 '17 at 16:13
@officialaimm: so how hard would it be to add another loop? – Martijn Pieters Apr 08 '17 at 16:15

How to transpose a dictionary in python, reverse mapping?

0 Answers0