Get max values in a nested dictionary returning with the keys-CodePudding

I'm new to Python and I need some help.

I have this nested dictionary:

diccionario = {
    "maria": {"valor1": 1, "valor2": 2}
}

And I want to extract the max value from the nested dictionary. I want this return: {"maria": valor2}

I have written this:

res = {clave: {clave: max(val.values())} for clave, val in diccionario.items()}



print (res)

But the return is: {'maria': {'maria': 2}}

I tried:

res = {clave: {clave: max(val.values())} for clave, val in diccionario.items()}

print (res)

return --> {'maria': {'maria': 2}}

I want:

{'maria': 'valor2'}

CodePudding user response：

You want the key of the maximum value, so let's do that. First, let's do it in a regular loop. Condensing it to a comprehension can happen later.

res = {}
for key, values_dict in diccionario.items():
    # Find the max of values_dict.items(). 
    # Each element of this is a tuple representing the key-value pair. 
    # The first element of the tuple is the key, the second is the value
    max_kvp = max(values_dict.items(), 
                  key=lambda kvp: kvp[1]) 
    # the key for max is the second item of the key-value pair (i.e. the value)

    # Now, max_kvp is the key-value pair that has the max value
    # Let's set the KEY of that pair as the value for res[key]
    res[key] = max_kvp[0]

Which gives the following res:

{'maria': 'valor2'}

As a dict comprehension:

# Find the max KVP by value     Take the first element of that KVP
# └----------v                                 └-------------v
res = {key: max(values_dict.items(), key=lambda kvp: kvp[1])[0] 
       for key, values_dict in diccionario.items()}

CodePudding user response：

You can use the key argument of the max function and set it to the accessor method of the dict:

{key: max(val, key=val.get) for key, val in diccionario.items()}