Unpack list of list python

Question

I know this has already been asked in other thread but I recall a neater way of doing this:

so here is a code that i know how to unpack things:

list = [[1, "tom"], [4, "jane"], [2, "peter"], [5.5, "Ursala"]]
points=[p for p, n in list]
name=[n for p, n in list]

So I know this is how I extract lists from list of list

but i remember there is some neater way of doing this. It's something like.

points,name = list

it gives me however the error: too many values to unpack (expected 2)

is this method for dictionary? not applicable for list of list?

Do *not* name your variable `list`; this is a built-in class name. — Booboo, Aug 14 '21 at 12:37

eroot163pi · Accepted Answer · 2021-08-14T12:41:53.237

3

Using zip you get tuples, convert those tuples to list using map

* is used for unpacking the iterable

l = [[1, "tom"], [4, "jane"], [2, "peter"], [5.5, "Ursala"]]
points,name = map(list, zip(*l))

# just to point out numpy is not only for numbers
import numpy as np
l = [[1, "tom"], [4, "jane"], [2, "peter"], [5.5, "Ursala"]]
ln = np.array(l)
points, name = ln[:, 0], ln[:, 1]

PS: list is already reserved by python use some other unreserved name

edited Aug 14 '21 at 12:41

answered Aug 14 '21 at 12:36

eroot163pi

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why not just `points,name = zip(*l)` – Mohammad Aug 14 '21 at 12:38
Hello. What does the asterisk mean? *l? – Wiley Ng Aug 14 '21 at 12:39
2

@Mohammad that would give tuples, `map(list, ...)` specifically gives lists – Alex Aug 14 '21 at 12:39
@WileyNg it's of [unpacking an iterable](https://docs.python.org/3/reference/expressions.html#expression-lists) – Alex Aug 14 '21 at 12:43
Thanks all so much! you guys are the best! – Wiley Ng Aug 14 '21 at 12:46
Accept if it helps and useful – eroot163pi Aug 14 '21 at 12:49

Unpack list of list python

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