issue in nested dictionary when try to iterate through value-CodePudding

why below code giving me error ?

nested_dict = {'first':{'a':1},'second':{'b':2}} {i for i in nested_dict.values()}

error:

TypeError Traceback (most recent call last) C:\Users\ABHINA~1\AppData\Local\Temp/ipykernel_12056/1167728052.py in ----> 1 {i for i in nested_dict.values()}

C:\Users\ABHINA~1\AppData\Local\Temp/ipykernel_12056/1167728052.py in (.0) ----> 1 {i for i in nested_dict.values()}

TypeError: unhashable type: 'dict'

CodePudding user response：

You are confused about notation.

Consider these two examples:

>>> {i  for i in [('a', 1), ('b', 2)]}
{('a', 1), ('b', 2)}
>>> 
>>> {k: v  for k, v in [('a', 1), ('b', 2)]}
{'a': 1, 'b': 2}

Using single variable i is asking for a set result. Each element of a set must be hashable, typically immutable, like tuple, str or int.

Using the key: value notation OTOH would be asking for a dict result.

CodePudding user response：

Hi actually i tried this and it works:

nested_dict = {'first':{'a':1},'second':{'b':2}} 

for i in nested_dict:
    for j in nested_dict[i]:
        print(j)

and also this works too :

nested_dict = {'first':{'a':1},'second':{'b':2}} 

for i in nested_dict.values():
    print(i)