如何在python中对字典中的特定值求和

Question

I have the following nested dictionary and need to figure out how to sum all 'qty'.

data1 = {
    'Batch1': {
        'Pink': {'qty': 25, 'ordered': 15},
        'Blue': {'qty': 18, 'ordered': 20}
    },
    'Batch2': {
        'Coke': {'qty': 50, 'ordered': 100},
        'Sprite': {'qty': 30, 'ordered': 25}
    }
}

So the outcomes would be 123.

Answer 1

You can use sum :

data1 = {'Batch1': {'Pink': {'qty': 25, 'ordered':15}, 'Blue': {'qty':18, 'ordered':20}}, 'Batch2': {'Coke': {'qty': 50, 'ordered': 100},'Sprite': {'qty':30, 'ordered':25}}}
result = sum(b['qty'] for c in data1.values() for b in c.values())

Output:

123

Answer 2

Your data1 was formatted funny, so here's what I used:

{'Batch1': {'Blue': {'ordered': 20, 'qty': 18},
  'Pink': {'ordered': 15, 'qty': 25}},
 'Batch2': {'Coke': {'ordered': 100, 'qty': 50},
  'Sprite': {'ordered': 25, 'qty': 30}}}

If you're not sure how deeply nested your dict will be, you can write a function to recursively traverse the nested dict looking for the qty key and sum the values:

def find_key_vals(query_key, base_dict):
    values = []
    for k, v in base_dict.items():
        if k == query_key:
            values.append(v)
        elif isinstance(v, dict):
            values += find_key_vals(query_key, v)
    return values

find_key_vals('qty', data1)
# => [50, 30, 25, 18]

sum(find_key_vals('qty', data1))
# => 123