如何过滤字典并将值存储在列表中？

Question

I want to search for similar values in a dictionary and store the value in a list. This is a little piece of the dictionary Load from yaml:

global_var:
  rt_id: 12345
var_rtr_a:
  subnet: 10.10.1.0/28
var_rtr_b:
  subnet: 10.10.2.0/28

I tried it with this code

key = ['subnet']
values = list(map(mydictionray.get, keys)
# Output: [none]

I understand why the output is None , because the key is not correct. But how can I define the correct key?

Answer 1

That's a dict of dicts.

Go for a recursive solution:

def recursive_key_search(key, lookup):
    if isinstance(lookup, dict):
        for _key in lookup.keys():
            if _key == key:
                output.append(lookup[key])
            recursive_key_search(key, lookup[_key])

Sample use:

test_dict = {
    'a': 'b',
    'c': {'d': 'e'}
}

output = []

recursive_key_search('d', test_dict)

print(output)
# >>> ['e']

Answer 2

i have edit my code into a function. Data is the dictionary

def search_dict(data):
    keys=['var_rtr_a','subnet','var_rtr_b','subnet']
    output=list(map(data.get,keys))
    print(output)
    return output

Output: [{'subnet': '10.10.1.0/28'}, None, {'subnet': '10.10.2.0/28'}, None]

But this is not what i need, i need only the values from the keys..

Answer 3

The way your data is formatted has it with a dictionary inside of a dictionary. When you look for subnet , you're only looking at the first layer of dictionaries, and not the second where subnet belongs.

One way of amending this that I can think of would be to iterate through the exterior values of the dictionary, and then search for subnet inside of those:

def search_dict(data):
     output = []
     for k in data:
          try:
               output.append(data[k]['subnet'])
     return output

This will correctly get every subnet from the dictionary and output it to a list.

Output:
['10.10.1.0/28', '10.10.1.0/28']

Answer 4

i changed my code to your example, but is does not work.

def search_dict(data):
    output = []
    for k in data:
        #try:
             output.append(data[k]['subnet'])
    return output

if __name__ == '__main__':
    data = read_file("data_input.yaml")
    search_dict(data)
    subnet = search_dict(data)
    print(subnet)

Output:
     29     for k in data:
     30         #try:
---> 31             output.append(data[k]['subnet'])
     32     #print(output)
     33     return output

KeyError: 'subnet'

Can we check the code again

Answer 5

ok, i try it with filtering with an example from this post:

How to filter a nested dictionary (pythonic way) for a specific value using map or filter instead of list comprehensions?

But it doesnt work with my dict.

Here my tests: Checks:

In [6]: data.values()
Out[6]: dict_values([{'rt_id': 12345}, {'subnet': '10.10.1.0/28'}, {'subnet': '10.10.2.0/28'}])

In [7]: data.items()
Out[7]: dict_items([('global_var', {'rt_id': 12345}), ('var_rtr_a', {'subnet': '10.10.1.0/28'}), ('var_rtr_b', {'subnet': '10.10.2.0/28'})])

In [8]: data.keys()
Out[8]: dict_keys(['global_var', 'var_rtr_a', 'var_rtr_b'])

In [11]: type(data)
Out[11]: dict

Here my filter with error:
In [12]: list(filter(lambda x: x['subnet'] , data.values()))
KeyError: 'subnet'

In [3]: list(filter(lambda x: x['var_rtr_a']['subnet'], data.values()))
KeyError: 'var_rtr_a'

Question: what is the right key for the filter? and wy is subnet not a right key?

So when i have an eays dict. the filters works fine