python - 嵌套字典 for 循环

Question

我是编程新手。我试图弄清楚如何从“实际”中减去“预算”，然后使用嵌套 for 循环将值更新为“方差”。但是，我读到在迭代时更改字典并不是最佳做法。到目前为止，我一直对如何进行感到困惑。

for i in properties:
    for j in properties[i]:
        if j == "actual":
            sum = properties[i][j]
            print('\nActual:' , sum)
        if j == "budgeted":
            sum_two = properties[i][j]
            print('Budgeted:' , sum_two)
            diff = sum_two - sum
            print('Variance:', diff)    

default_value = 0

properties = {587: {'prop_name': 'Collington'}, 'rental_income': {'apartment_rent': '5120-0000', 'resident_assistance': '5121-0000', 'gain_loss': '5120-0000'}, 51200000: {'actual': 29620, 'budgeted': 30509, 'variance': default_value}, 51210000: {'actual': 25620, 'budgeted': 40509, 'variance': default_value}, ............

Answer 1

只需遍历字典并检查是否在内部字典中，actual、variance 和 budgeted 是否存在，如果存在则修改方差值

for k, v in properties.items():
    if (('actual' in v.keys()) and ('variance' in v.keys()) and ('budgeted' in v.keys())):
            properties[k]['variance'] = properties[k]['actual']-properties[k]['budgeted']