Make variable the name of a list? Python

Question

I want each variable put into this function to then become the name of its own list.

def listy(x, insert):
    listend = isinstance(x, list)
    if listend:
        x.append(insert)
    else:
        x = []
        x.append(insert)
    print(x)

listy("xyz", "neutral")
listy("xyz", "happy")

When I do this, though, it overwrites the previous list (ends up with the list just reading "happy" instead of "neutral", "happy"). How do I get it to append if that word is already the name of a list?

isinstance is not turning it into a list. It's returning a boolean. Then your creating a list called x since it returns False then appending insert. — Buddy Bob, Apr 21 '21 at 01:23
[Duplicate?](https://stackoverflow.com/questions/1373164/how-do-i-create-variable-variables) — 12944qwerty, Apr 21 '21 at 01:27
@BuddyBobIII Makes sense. I tried to reverse the if/else, but now I'm getting an AttributeError for str not having list — UriGroup, Apr 21 '21 at 01:29

score 0 · Answer 1 · answered Apr 21 '21 at 01:32

0

Here this works for the example you gave. It uses dictionaries.

def listy(x, insert):
    varName[x].append(insert)
    return varName
varName = {"xyz":[]}
x = listy("xyz", "neutral")
y=listy("xyz", "happy")
print(y)

answered Apr 21 '21 at 01:32

Buddy Bob

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Silentroar · Answer 2 · 2021-04-21T01:46:53.223

it overwrites the previous list ..

The previous list is not overwritten. The list created inside the function listy is auto destroyed by garbage collector. You are simply creating a new temporary list in second function call listy("xyz", "happy"), which will be destroted again. You need to put x in global context.

You can rewrite the function this way:

def listy(x, insert):
    listend = isinstance(x, list)
    if listend:
        x.append(insert)
    else:
        x = []
        x.append(insert)
    print(x)
    return x

x = listy("xyz", "neutral")
x = listy(x, "happy")

You seem to have confusion about references and objects. In python, everything is an object. A name like x is just a reference to an object. There is no way x in the second function call can refer to ["neutral"] created and destroyed in the first function call.

Make variable the name of a list? Python

2 Answers2