使用Python以相同的顺序从CSV创建字典列表

Question

Consider a CSV,

col1, col2, col3
1000, Star, True
2000, Moon, False

How to create a list of dictionaries in the same order like this

[{'col1': '1000', 'col2': 'Star', 'col3': 'TRUE'}, {'col1': '2000', 'col2': 'Moon', 'col3': 'FALSE'}]

I have tried with following code but not getting in the same order

with open('sample.csv') as f:
    rows = [{k: v for k, v in row.items()}
        for row in csv.DictReader(f, skipinitialspace=True)]

Output of above code,

[{'col2': 'Star', 'col3': 'TRUE', 'col1': '1000'}, {'col2': 'Moon', 'col3': 'FALSE', 'col1': '2000'}]

Is there any solution to get in the same order?

Thanks!

Answer 1

Since dictionaries are inherently unordered, you need wrap an OrderedDict on each of the dictionaries in your list, which need to be sorted beforehand:

import csv
from collections import OrderedDict

with open('sample.csv') as f:
    rows = [OrderedDict(sorted(dict((k, v) for k, v in row.items()).items())) for row in csv.DictReader(f, skipinitialspace=True)]

>>> print(rows)
[OrderedDict([('col1', '1000'), ('col2', 'Star'), ('col3', 'True')]), OrderedDict([('col1', '2000'), ('col2', 'Moon'), ('col3', 'False')])]

And works normally:

>>> print(rows[0]['col1'])
1000
>>> print(rows[1]['col1'])
2000
print([key for key in rows[0]])
['col1', 'col2', 'col3']

Note: You can't replace the OrderedDict() wrapping in the output with a normal dictionary, otherwise it will be unordered again. This is one of the prices we have to pay if we want ordered dictionaries in python.