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I am struggling to find a way to assign a value from a list to names from another pre-defined list with Table[].

names = {first, second, third}
numbers = {{1, 1}, {2, 2}, {3, 3}}

What I want is:

first = {1, 1}
second = {2, 2}
third = {3, 3}

so that {1, 1} is stored in first etc.

I tried the following:

namelists = Table[(names[[i]]) = (numbers[[i]]), {i, Length[names]}];

In this case, namelists[[1]] = {1, 1}, however first does not store any information...

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    $\begingroup$ If you are not set on using Table then MapThread[Set, {names, numbers}] $\endgroup$
    – Edmund
    Commented Dec 23, 2019 at 12:44

4 Answers 4

11
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Clear[first, second, third]
names = {first, second, third}
numbers = {{1, 1}, {2, 2}, {3, 3}}
Table[Evaluate[names[[i]]] = numbers[[i]], {i, 3}]
first
second
third
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    $\begingroup$ Since you can make multiple assignments at the same time, you don't need the Table: the "vectorized" Evaluate@names = numbers will work too. $\endgroup$
    – MarcoB
    Commented Dec 23, 2019 at 15:50
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Clear[first, second, third]    

names = {first, second, third};
numbers = {{1, 1}, {2, 2}, {3, 3}};

With[{names = names}, names = numbers];

first

{1, 1}

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8
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With the following definitions:

Clear[first, second, third]
names = {first, second, third}
numbers = {{1, 1}, {2, 2}, {3, 3}}

a one-liner approach would be:

Evaluate@names = numbers

You can see how this works using Trace:

Clear[first, second, third]
names = {first, second, third}
numbers = {{1, 1}, {2, 2}, {3, 3}}
Trace[Evaluate@names = numbers]

(* Out: 
{{names, {first, second, third}}, 
   {numbers, {{1, 1}, {2, 2}, {3, 3}}}, 
   {first, second, third} = {{1, 1}, {2, 2}, {3, 3}}, 
   {{1, 1}, {2, 2}, {3, 3}}} *)
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6
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MapThread works well for this task.

numbers = {{1, 1}, {2, 2}, {3, 3}};
Clear[first, second, third]
names = {first, second, third};
MapThread[Set, {names, numbers}]; 
{first, second, third}

{{1, 1}, {2, 2}, {3, 3}}

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