Question

How to flatten a nested dictionary in Python

Answer 1

def flatten_nested_dict(dic, parent_key='', sep='_'):
    items = []
    for key, val in dic.items():
        new_key = parent_key + sep + str(key) if parent_key else str(key)
        if isinstance(val, dict):
            items.extend(flatten_nested_dict(val, new_key, sep=sep).items())
        else:
            items.append((new_key, val))
            
    return dict(items)
    
nested_dict = {
    0: {'key1':34, 'key2':89, 'key3':12},
    1: {'key4':72, 'key5':90}
}
 
flat_dict = flatten_nested_dict(nested_dict)

print(flat_dict) 
 
 
 
'''
run:
 
{'0_key1': 34, '0_key2': 89, '0_key3': 12, '1_key4': 72, '1_key5': 90}
 
'''

 

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