dic={}
dic[1]=100
dic[2]=200
dic[1]+=500
here I have initialed a dictionary and I am able to update the key value of the dictionary. But keys in dictionary are immutable, so what's actually happening , can someone please tell?
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1You are not modifying the key, you are modifying the value of a key. – Asocia Jun 16 '20 at 15:30
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You can find answer here https://stackoverflow.com/questions/24217647/why-must-dictionary-keys-be-immutable – Jason Yang Jun 16 '20 at 15:33
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Just think of it this way. We have an empty dictionary:
d = {}
If we do this:
d[1] = 100
we are simply adding a key and assigning a value to that key, right then and there.
Just like sets, dicts cannot have duplicate keys, so adding another key with the same name will overwrite the original.
Like doing calling d[1] = 200 will overwrite the original d[1].
d[1] += 500 is the same as:
d[1] = d[1]+500
where we are simply telling python to add a key to d called 1, and assign the value of the original key plus 500 to that key.
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