CODEWITHSUNDEEP
pythonpython-3.x
Evan Brittain
Evan Brittain

Reputation: 587

Pythonic way to modify a list of dictionaries

Looking for an efficient way to modify a dictionary

I have a list of dictionaries in this format:

>>> x = [{'server': 's1', 'disk' : 'd1', 'size': 10},{'server': 's2', 'disk' : 'd2', 'size': 20},{'server': 's3', 'disk' : 'd3', 'size': 30}, {'server': 's1', 'disk' : 'd4', 'size': 40}]

I'd like it to be restructured so the value of 'server' becomes the key and contains a list of dictionaries with disk and size information that are all within that server

{'s1': [{'disk': 'd1', 'size': 10}, {'disk': 'd4', 'size': 40}], 's2': [{'disk': 'd2', 'size': 20}], 's3': [{'disk': 'd3', 'size': 30}]}

This is what ive tried:

>>> y = {y[i.pop('server')].append(i) if i['server'] in y else i.pop('server'): [i] for i in x}
>>> y
{'s1': [{'disk': 'd4', 'size': 40}], 's2': [{'disk': 'd2', 'size': 20}], 's3': [{'disk': 'd3', 'size': 30}]}

>>> out = {'s1' : [{'disk' : 'd1', 'size': 10},{'disk' : 'd4', 'size': 40}], 's2' : [{'disk' : 'd2', 'size': 20}], 's3' : [{'disk' : 'd3', 'size': 30}]}

Upvotes: 1

Views: 135

Answers (1)

Devesh Kumar Singh
Devesh Kumar Singh

Reputation: 20490

The approach you have is fine, but I might suggest creating a new dictionary instead of modify what we already have For that, you can iterate over the list and create your required dictionary as follows

x = [{'server': 's1', 'disk' : 'd1', 'size': 10},{'server': 's2', 'disk' : 'd2', 'size': 20},{'server': 's3', 'disk' : 'd3', 'size': 30}, {'server': 's1', 'disk' : 'd4', 'size': 40}]

from collections import defaultdict

dct = defaultdict(list)

#Iterate over the list
for item in x:
    #Use server value as key, and the remainining k,v pairs as dict and append them to a list
    dct[item['server']].append({k:v for k,v in item.items() if k != 'server'})

print(dict(dct))

Or if you want to follow the dict.pop() approach, pop the key server and use it as a key in your dictionary

x = [{'server': 's1', 'disk' : 'd1', 'size': 10},{'server': 's2', 'disk' : 'd2', 'size': 20},{'server': 's3', 'disk' : 'd3', 'size': 30}, {'server': 's1', 'disk' : 'd4', 'size': 40}]

from collections import defaultdict

dct = defaultdict(list)

#Iterate over the list
for item in x:
    #Get server value after popping server key
    server = item.pop('server')

    #Use that value and append the remaining dict to a list
    dct[server].append(item)

print(dict(dct))

The output will be same in both cases, which is

{'s1': [{'disk': 'd1', 'size': 10}, {'disk': 'd4', 'size': 40}], 's2': [{'disk': 'd2', 'size': 20}], 's3': [{'disk': 'd3', 'size': 30}]}

Upvotes: 1

Related Questions