将嵌套字典转换为元组 python

Question

I want to convert nested dictionaries into tuples. I have tried but I didn't get the expected results. I want to do it without a list comprehension

Following is the dictionary

test_dict = {'Layer 4': {'start_2': '38.52', 'start_1': '35.15'}}

Following is my code

# printing original dictionary 
print("The original dictionary is : " + str(test_dict)) 
  
# Convert Nested dictionary to Mapped Tuple 
# Using list comprehension + generator expression 
res = [(key, tuple(sub[key] for sub in test_dict.values()))  
                               for key in test_dict['Layer 4']] 
  
# printing result  
print("The grouped dictionary : " + str(res)) 

Results that I have got

The original dictionary is : {'Layer 4': {'start_2': '38.52', 'start_1': '35.15'}}
The grouped dictionary : [('start_2', ('38.52',)), ('start_1', ('35.15',))]

And I am expecting the following output without mentioning the first key of the dictionary

[('Layer 4', 'start_2','38.52'), ('Layer 4','start_1', '35.15')]

Answer 1

There are many ways to do this. Here is one:

>>> d={'a':{'b':1,'c':2}}
>>> sum([ [ (k, *w) for w in v.items() ] for k, v in d.items() ], [])
[('a', 'b', 1), ('a', 'c', 2)]

Answer 2

the problem is that you do one the comprehension inside the tuple and over the values, do it over the items instead, and the second level over the items of those

>>> test_dict = {'Layer 4': {'start_2': '38.52', 'start_1': '35.15'}}
>>> [ (key,*item) for key,value in test_dict.items() for item in value.items()]
[('Layer 4', 'start_2', '38.52'), ('Layer 4', 'start_1', '35.15')]
>>> 
>>> [ item for key,value in test_dict.items() for item in value.items()]
[('start_2', '38.52'), ('start_1', '35.15')]
>>> 

actually you don't need items if you don't care for the keys of the outer dict

>>> [ item for value in test_dict.values() for item in value.items()]
[('start_2', '38.52'), ('start_1', '35.15')]
>>> 

a little esoteric way of doing it

>>> list(*map(dict.items,test_dict.values()))
[('start_2', '38.52'), ('start_1', '35.15')]
>>> 

but that doesn't quite work if for example we got another key in the outer dict

>>> test_dict2 = {'Layer 4': {'start_2': '38.52', 'start_1': '35.15'}, 'Layer 
23': {'start_23': '138.52', 'start_13': '135.15'}}
>>> [ item for value in test_dict2.values() for item in value.items()]
[('start_2', '38.52'), ('start_1', '35.15'), ('start_23', '138.52'), 
('start_13', '135.15')] 
>>>

to get the same in a more esoteric way, we can use itertools for that

>>> import itertools
>>> list(itertools.chain.from_iterable(map(dict.items,test_dict2.values())))
[('start_2', '38.52'), ('start_1', '35.15'), ('start_23', '138.52'), 
('start_13', '135.15')]
>>>