Appending item to a list within dictionary without checking if the key exists

Question

Currently, in order to do what I'm describing, I have a code like this:

if key in dict:
    dict[key].append(item)
else:
    dict[key] = [item]

Is there any way I can append to list within dictionary without doing the explicit check?

Can this be done using another data structure?

What I need to do is to track all the items that have some parameter equal.

Are you sure `dict[key] = item` is correct? Shouldn't that be `dict[key] = [item]`? — Aran-Fey, Sep 11 '18 at 11:21
I think it works either way. I'll change it to make it less confusing. — Karlovsky120, Sep 11 '18 at 11:22
You probably want a `defaultdict`. It was made for exactly this situation — Wolf, Sep 11 '18 at 11:22

score 0 · Accepted Answer · answered Sep 11 '18 at 11:23

d = {}    
d.setdefault(1, []).append('item')

in python .get used to retrieve key and optional argument to get if value not exist, however it will give you only initial value. whereas in .setdefault you will get a value for corresponding key or else it will initialise key with default value passed as another argument

Appending item to a list within dictionary without checking if the key exists

1 Answers1