Get the following error in code, unsure of what it means or what I did wrong. Just trying to initialize three list values to empty collections:
nba,nfl,mlb = []
ValueError: not enough values to unpack (expected 3, got 0)
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What did you find when you searched for information about the error? What about that information seemed insufficient or was confusing?jpmc26– jpmc262018-08-24 20:43:15 +00:00Commented Aug 24, 2018 at 20:43
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@jpmc26 there was not sufficient material on a google search for initializing multiple lists in a single line. I'm sure you'll _standdang– dang2018-08-27 19:41:54 +00:00Commented Aug 27, 2018 at 19:41
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That is simply not true. google.com/… And the first result: stackoverflow.com/q/2402646/1394393 The second answer contains exactly the syntax you accepted.jpmc26– jpmc262018-08-27 19:57:39 +00:00Commented Aug 27, 2018 at 19:57
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4 Answers
The issue is , left hand side values are not enough to assign to the number of variable on the left so instead do
nba,nfl,mlb = [],[],[]
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This attempts to unpack, as the error message says, an iterable on the right hand side into three variables on the left hand side, so, for example, after running a,b,c = 1,2,3 you get a == 1 and b == 2 and c == 3.
In your case, this iterable is empty, so "there are not enough values to unpack": there are three variables, but no values in the iterable (the iterable is an empty list). What you need is the following:
a,b,c = [],[],[]
Here you have three variables a,b,c and the iterable discussed above is the tuple [],[],[] in this case.
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Another option if you want to unpack a generator for instance:
nba,nfl,mlb = [[] for _ in range(3)]
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basically means left hand side has more values than right hand side of =
nba = nfl = mlb = [] should get you three list values initialized to empty collections. So should nba, nfl, mlb = [], [], []
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dang
would the first solution result in three variable pointing at the same list?