Python 3 (1) Dictionary Python Upper Case Values Present In A Single Key. (2) Why Datatype Sets In Python Does Not Return True Element?

(1) A snippet that takes a dictionary and uppercases every value in the dictionary and sets that value back into the dictionary at the same key e.g. Given: d = {'a': ['amber', 'ash

Solution 1:

(1)

d2 = {key:[name.upper() for name in names] for key, names in d.items()}

(2)

That seems to be because True == 1 yields True, which is what the Set uses to check if the value added is already in the Set and therefore has to be ignored.

Solution 2:

Your attempt is:

d.update((k, v.upper()) for k,v in d.items())

That doesn't work that way. For instance, v is a list, you cannot upper a list...

This kind of transformation is better done using a dictionary comprehension to rebuild a new version of d. You can do the upper part for each value using list comprehension:

d = {k:[v.upper() for v in vl] for k,vl in d.items()}

For your second question: since 1==True, the set keeps only the first inserted, which here is 1. but could have been True: example:

>>>{True,1}
{1}
>>>{True,1,True}
{True}
>>>{1,True}
{True}
>>>

more deterministic: pass a list to build the set instead of using the set notation:

>>>set([True,1])
{True}
>>>set([1,True])
{1}

Solution 3:

(1) Could be shorter, just in one line as shown by others answers, but here is trade off between complexity and "Pythonicity":

d = {'a': ['amber', 'ash'], 'b': ['bart', 'betty']}
for k in d:
    d[k] = [i.upper() for i in d[k]]

print(d)

OUTPUT:

{'a': ['AMBER', 'ASH'], 'b': ['BART', 'BETTY']}

(2) Because True == 1 is true and Python set objects just have items that are differences between them.