Array to Dictionary Output Python

Question

I have the following list after querying my DB which I'd like to turn into a dictionary:

[{date: date_value1.1, rate: rate_value1.1, source: source_name1},
{date: date_value1.2, rate: rate_value1.2, source: source_name1},
{date: date_value2.1, rate: rate_value2.1, source: source_name2},
{date: date_value2.2, rate: rate_value2.2, source: source_name2},
{date: date_valuenx, rate: rate_valuex, source: source_namex}, ...]

The dictionary should follow the following format:

{
  source_name1:
    [
      {date: date_value1.1, rate: rate_value1.1}
      {date: date_value1.2, rate: rate_value1.2}
    ],
  source_name2:
    [
      {date: date_value2.1, rate: rate_value2.1}
      {date: date_value2.2, rate: rate_value2.2}
    ],
}

I have tried a lot of different code variations, but could not get it to work. What would be the most efficient way to transform the data into the required format?

(This format is the response the client will receive after calling my API. If you have suggestions for better formatting of this response I am also open to suggestions!)

PacketLoss · Accepted Answer · 2021-05-06 04:57:28Z

2

We can use defaultdict and simply append each result to our output list.

from collections import defaultdict

output = defaultdict(list)

data = [{'date': 'date_value1.1', 'rate': 'rate_value1.1', 'source': 'source_name1'}, {'date': 'date_value1.2', 'rate': 'rate_value1.2', 'source': 'source_name1'}, {'date': 'date_value2.1', 'rate': 'rate_value2.1', 'source': 'source_name2'}, {'date': 'date_value2.2', 'rate': 'rate_value2.2', 'source': 'source_name2'}, {'date': 'date_valuenx', 'rate': 'rate_valuex', 'source': 'source_namex'}]

for row in data:
    output[row['source']].append({k: v for k, v in row.items() if k != 'source'})

dict(output)
#{'source_name1': [{'date': 'date_value1.1', 'rate': 'rate_value1.1'}, {'date': 'date_value1.2', 'rate': 'rate_value1.2'}], 'source_name2': [{'date': 'date_value2.1', 'rate': 'rate_value2.1'}, {'date': 'date_value2.2', 'rate': 'rate_value2.2'}], 'source_namex': [{'date': 'date_valuenx', 'rate': 'rate_valuex'}]}

import pprint

pprint.pprint(dict(output))

{'source_name1': [{'date': 'date_value1.1', 'rate': 'rate_value1.1'},
                  {'date': 'date_value1.2', 'rate': 'rate_value1.2'}],
 'source_name2': [{'date': 'date_value2.1', 'rate': 'rate_value2.1'},
                  {'date': 'date_value2.2', 'rate': 'rate_value2.2'}],
 'source_namex': [{'date': 'date_valuenx', 'rate': 'rate_valuex'}]}

edited May 6, 2021 at 4:57

answered May 6, 2021 at 4:53

PacketLoss

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3 Comments

edusanketdk Over a year ago

Match his expected output with yours first.

PacketLoss Over a year ago

@edusanketdk The output matches for his example.

Tobias Heckmann Over a year ago

This achieved exactly what I was looking for. Thank you!

Amit Nanaware · Accepted Answer · 2021-05-06 04:59:58Z

1

try this:

d = [{"date":" date_value1.1", "rate": "rate_value1.1", "source": "source_name1"},
{"date": "date_value1.2", "rate": "rate_value1.2", "source": "source_name1"},
{"date": "date_value2.1", "rate": "rate_value2.1", "source": "source_name2"},]
    
d1 = {}
for ele in d:
    key = ele.pop('source')
    d1[key] = d1.get(key, list())
    d1[key].append(ele)

print(d1)

output is:

{'source_name1': [{'date': ' date_value1.1', 'rate': 'rate_value1.1'}, {'date': 'date_value1.2', 'rate': 'rate_value1.2'}], 'source_name2': [{'date': 'date_value2.1', 'rate': 'rate_value2.1'}]}

edited May 6, 2021 at 4:59

answered May 6, 2021 at 4:55

Amit Nanaware

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2 Comments

sushanth Over a year ago

Does not match with what OP needs.

sushanth Over a year ago

Or you could also do, d1.setdefault(ele.pop('source'), []).append(ele)

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