Question

Let’s say we have:

from collections import defaultdict
original_dict = { 'somegroupofelements':{'name':1, 'group':1 ,'results':[1,2,3,4]}, 'somegroupofelements2':{'name':2, 'group': 2 ,'results':[1,2,3,4]}, 'somegroupofelements3':{'name':3, 'group':3 ,'results':[1,2,3,4]} }

new_dict = defaultdict(list)

for key, value in original_dict.iteritems():
    # i need to organize things grouped for making the right latex tables
    # and for updating some values...
    value['key']=key
    new_dict[value['group']].append(value)

I want that new_dict, after I’ve done my work, to be organized again just like the original_dict? Like reconstruct the original_dict from the new_dict.

Answer 1

So you end up with a dictionary in the form:

>>> d = { 100 : [{'name':1, 'group':100, 'key':'group1'}, 
...              {'name':2, 'group':100, 'key':'group2'}],
...       200 : [{'name':3, 'group':200, 'key':'group3'}] }

Which can be transformed back into a dictionary using a dict comprehension:

>>> orig = { x['key']:x for v in d.values() for x in v }
>>> orig
{'group1': {'group': 100, 'name': 1, 'key': 'group1'}, 
 'group3': {'group': 200, 'name': 3, 'key': 'group3'}, 
 'group2': {'group': 100, 'name': 2, 'key': 'group2'}}

If you want, you can then delete the superflous key field of the items:

>>> for v in orig.values(): del v['key']
...
>>> orig
{'group1': {'group': 100, 'name': 1}, 
 'group3': {'group': 200, 'name': 3}, 
 'group2': {'group': 100, 'name': 2}}