[erlang-questions] [erlang-question] How to comprehend two lists synchronously?

lenartlad <>
Fri Nov 18 06:57:10 CET 2011


Hello.

Use lists:zip/2:

lists:zip([a,b,c], [1,2,3]) -> [{a,1},{b,2},{c,3}]


HTH,

Ladislav Lenart


----- PŮVODNÍ ZPRÁVA -----
Od: "Barco You" <>
Komu: "erlang-questions" <>
Předmět: [erlang-questions] [erlang-question] How to comprehend two
Datum: 18.11.2011 - 6:45:58

> Dear Erlangers,
> 
> 
> I hope to get a list from two lists like this:
> [{a1,b1}, {a2,b2}, {a3,b3}]      <-     [a1, a2
> a3],  [b1, b2, b3].
> 
> But if I use list comprehension, I got:
> 10>  [{D1,D2} ||  D1 <- [a1,a2,a3], D2 <-
> [b1,b2,b3]].
> [{a1,b1},
> {a1,b2},
> {a1,b3},
> {a2,b1},
> {a2,b2},
> {a2,b3},
> {a3,b1},
> {a3,b2},
> {a3,b3}]
> 
> 
> So, my questions is how to comprehend list in
> synchronous way in order to
> get what I want, rather than to compose the
> elements from two lists in all
> possible situations.
> 
> 
> Thank you,
> Barco
> 


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