On 2017-03-08 21:14, boB Stepp wrote:
Alex, I think you can break this down as follows:
py3: res = {}
py3: def key_item_to_res(item):
... res.setdefault(item, []).append(item)
...
py3: key_item_to_res(3)
py3: res
{3: [3]}
py3: key_item_to_res(3)
py3: res
{3: [3, 3]}
py3: key_item_to_res(2)
py3: res
{3: [3, 3], 2: [2]}
I think you can play with this and see how Alan's code works. The
setdefault(item, []) method checks the dictionary it is acting on for
the key, "item". If it finds it then it will execute the
"append(item)" method on the sublist attached to that key. If it does
not find it, then it creates a new key, "item", attaches the empty
list, "[]", to that key, and then appends item to that empty list.
boB
It seems you are simply kicking the can down the road rather than
explaining how it it is that dot notation actually works.
To access a dictionary item one must specify it by name_of_dict[key].
What Allan is (and you also are) doing is using dot notation.
Your example uses side effects (which I've been lead to believe is a no
no.)
The dot notation works (to my surprise) and I was hoping for an
explanation of just what is happening.
a
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