Filtering dict of dict with dictionary comprehension

Question

I have problem with filtering dict of dict while using dict comprehension.

I have dict:

clients = {
        'Shop': {'url' : 'url_v', 'customer' : 'cumoster_v', 
                 'some_other_key1' : 'some_value'},
        'Gym': {'url' : 'url_v1', 'customer_1' : 'customer_v1', 'customer_2': 'customer_v2',
                 'some_other_key2' : 'some_value'},
        'Bank': {'url' : 'url_v2', 'customer_3' : 'customer_v3',    
                  'some_other_key3' : 'some_value'}
}

I would like to make another dict which will have only 'customer.*' keys. So, new dict should looks like:

dict_only_cust = {
               'Shop': {'customer' : 'cumoster_v'},
               'Gym': {'customer_1' : 'customer_v1', 'customer_2': 'customer_v2'},
               'Bank': {'customer_3' : 'customer_v3'}
}

As I'm big fan of lists and dicts comprehension, I'm wondering if it is possible to do it with this.

So far, I've written:

dict_only_cust = {v.pop(t) for k, v in clients.items()
                for t, vv in v.items()
                if not re.match('.*customer.*', t)}

Code fails with 'RuntimeError: dictionary changed size during iteration'

Second time I've tried:

dict_only_cust = {k:{t: vv} for k, v in clients.items()
                for t, vv in v.items()
                if re.match('.*customer.*', t)}

It is almost OK, but it is returning

dict_only_cust = {
              'Shop' : {'customer' : 'cumoster_v'},
              'Gym' : {'customer_1' : 'customer_v1'},
              'Bank' : {'customer_3' : 'customer_v3'}
}

How to solve this problem using dict comprehension? I'm using python 3.4.

Thanks!

Answer 1

>>> {key:{k:v for k,v in dic.items() if 'customer' in k} for key,dic in clients.items()}
{'Shop': {'customer': 'cumoster_v'}, 'Gym': {'customer_2': 'customer_v2', 'customer_1': 'customer_v1'}, 'Bank': {'customer_3': 'customer_v3'}}

Answer 2

{k:{k1:v1 for  k1,v1 in v.items() if k1.startswith('customer')} for k, v in clients.items()}

输出：

{'Shop': {'customer': 'cumoster_v'}, 'Gym': {'customer_2': 'customer_v2', 'customer_1': 'customer_v1'}, 'Bank': {'customer_3': 'customer_v3'}}