json flatten.py

def get_records():
    df = pandas.read_json('1.json')
    df = pandas.io.json.json_normalize(df['accidents'])
    for _, row in df.iterrows():
        for c in row['casualties']:
            for i in row['involved']:
                row['caualty_severity'] = c['severity']
                row['caualty_gender'] = c['gender']
                row['caualty_class'] = c['class']
                row['caualty_vehicle'] = c.get('vehicle', 'unknonwn')
                row['involved_id'] = i['id']
                row['involved_type'] = i['type']
                yield row
                
df = pandas.DataFrame.from_records(get_records())
del df['casualties']
del df['involved']