python list of dictionaries find duplicates based on value

Question

I have a list of dicts in python 2.7.

a =[{\'id\': 1,\'desc\': \'smth\'},
    {\'id\': 2,\'desc\': \'smthelse\'},
    {\'id\': 1,\'desc\': \'smthelse2\'},
          


        

Answer 1

It is better to keep the "desc" values as lists everywhere even if they contain a single element only. This way you can do

for d in b:
    print d['id']
    for desc in d['desc']:
        print desc

This would work for strings too, just returning individual characters, which is not what you want.

And now the solution giving you a list of dicts of lists:

a =[{'id': 1,'desc': 'smth'},{'id': 2,'desc': 'smthelse'},{'id': 1,'desc': 'smthelse2'},{'id': 1,'desc': 'smthelse3'}]

c = {}
for d in a:
    c.setdefault(d['id'], []).append(d['desc'])
b = [{'id': k, 'desc': v} for k,v in c.iteritems()]

b is now:

[{'desc': ['smth', 'smthelse2', 'smthelse3'], 'id': 1},
 {'desc': ['smthelse'], 'id': 2}]