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pythonjsonpandasdataframenormalize

Pandas - normalize Json list


I am trying to normalize a column from a Pandas dataframe that is a list of dictionaries (can be missing).

Example to reproduce

import pandas as pd
bids = pd.Series([[{'price': 606, 'quantity': 28},{'price': 588, 'quantity': 29},
                   {'price': 513, 'quantity': 33}],[],[{'price': 7143, 'quantity': 15},
                    {'price': 68, 'quantity': 91},{'price': 6849, 'quantity': 12}]])
data = pd.DataFrame([1,2,3]).rename(columns={0:'id'})
data['bids'] = bids

Desired output

id price quantity
1  606    28
1  588    29
1  513    33
3  7143   15
3  68     91
3  6849   12

Attempt

Trying to resolve using pandas json_normalize, following docs here. I'm confused by why none of the below work, and what type of record_path will fix my problem. All the below error.

pd.json_normalize(data['bids'])
pd.json_normalize(data['bids'],['price','quantity'])
pd.json_normalize(data['bids'],[['price','quantity']])

Solution

  • Adding another approach with np.repeat and np.concatenate with json_normalize

    out = pd.io.json.json_normalize(np.concatenate(data['bids']))
    out.insert(0,'id',np.repeat(data['id'],data['bids'].str.len()).to_numpy())
    

    Or you can also use np.hstack as @Shubham mentions instead of np.concatenate:

    out = pd.io.json.json_normalize(np.hstack(data['bids']))
    

    print(out)
    
       id  price  quantity
    0   1    606        28
    1   1    588        29
    2   1    513        33
    3   3   7143        15
    4   3     68        91
    5   3   6849        12