CODEWITHSUNDEEP
pythondictionary
schlumpfpirat
schlumpfpirat

Reputation: 195

Group List of Dicts by Key in Python

Looking for a Pythonic way to iterate over a list of Dicts and group them by a certain key.

E.g. a list like this should be grouped by position

[
    {'Name': 'Bradley Greer', 'Position': 'Software Engineer', 'Office': 'London', 'Age': '41', 'Start date': '2012/10/13', 'Salary': '$132,000'},
    {'Name': 'Brenden Wagner', 'Position': 'Software Engineer', 'Office': 'San Francisco', 'Age': '28', 'Start date': '2011/06/07', 'Salary': '$206,850'},
    {'Name': 'Bruno Nash', 'Position': 'Software Engineer', 'Office': 'London', 'Age': '38', 'Start date': '2011/05/03', 'Salary': '$163,500'},
    {'Name': 'Cara Stevens', 'Position': 'Sales Assistant', 'Office': 'New York', 'Age': '46', 'Start date': '2011/12/06', 'Salary': '$145,600'},
    {'Name': 'Donna Snider', 'Position': 'Customer Support', 'Office': 'New York', 'Age': '27', 'Start date': '2011/01/25', 'Salary': '$112,000'},
    {'Name': 'Doris Wilder', 'Position': 'Sales Assistant', 'Office': 'Sydney', 'Age': '23', 'Start date': '2010/09/20', 'Salary': '$85,600'},
    {'Name': 'Gavin Joyce', 'Position': 'Sales Assistant', 'Office': 'Edinburgh', 'Age': '42', 'Start date': '2010/12/22', 'Salary': '$92,575'},
    {'Name': 'Herrod Chandler', 'Position': 'Sales Assistant', 'Office': 'San Francisco', 'Age': '59', 'Start date': '2012/08/06', 'Salary': '$137,500'}
]

would result in something like this

[
    {
        'Position': 'Software Engineer',
        'Items': [
                {'Name': 'Bradley Greer', 'Position': 'Software Engineer', 'Office': 'London', 'Age': '41', 'Start date': '2012/10/13', 'Salary': '$132,000'},
                {'Name': 'Brenden Wagner', 'Position': 'Software Engineer', 'Office': 'San Francisco', 'Age': '28', 'Start date': '2011/06/07', 'Salary': '$206,850'},
                {'Name': 'Bruno Nash', 'Position': 'Software Engineer', 'Office': 'London', 'Age': '38', 'Start date': '2011/05/03', 'Salary': '$163,500'},
        ]
    },
    {
        'Position': 'Sales Assistant',
        'Items': [
            {'Name': 'Cara Stevens', 'Position': 'Sales Assistant', 'Office': 'New York', 'Age': '46', 'Start date': '2011/12/06', 'Salary': '$145,600'},
            {'Name': 'Doris Wilder', 'Position': 'Sales Assistant', 'Office': 'Sydney', 'Age': '23', 'Start date': '2010/09/20', 'Salary': '$85,600'},
            {'Name': 'Gavin Joyce', 'Position': 'Sales Assistant', 'Office': 'Edinburgh', 'Age': '42', 'Start date': '2010/12/22', 'Salary': '$92,575'},
            {'Name': 'Herrod Chandler', 'Position': 'Sales Assistant', 'Office': 'San Francisco', 'Age': '59', 'Start date': '2012/08/06', 'Salary': '$137,500'}
        ]
    },
    {
        'Position': 'Customer Support',
        'Items': [
            {'Name': 'Donna Snider', 'Position': 'Customer Support', 'Office': 'New York', 'Age': '27', 'Start date': '2011/01/25', 'Salary': '$112,000'},
        ]
    }
]

Upvotes: 0

Views: 475

Answers (2)

Ghilas BELHADJ
Ghilas BELHADJ

Reputation: 14096

You can use itertools.groupby

items is your input list

import itertools

output = []
for k,v in itertools.groupby(items, key=lambda x:x['Position']):
  output += [{
    'Position': k,
    'Items': list(v)
  }]

Upvotes: 3

saedx1
saedx1

Reputation: 1075

If you want a one-liner (nearly as fast as the previous solution), then here it is:

people = # Your list of dicts
key = "Position" # The key to group by

output = [
    {key: k, "items": [person for person in people if person[key] == k]}
    for k in {person[key] for person in people}
]

Upvotes: 2

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