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MathGroup Archive 2002

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Re: Import variable and data

  • To: mathgroup at smc.vnet.net
  • Subject: [mg32745] Re: [mg32696] Import variable and data
  • From: Andrzej Kozlowski <andrzej at platon.c.u-tokyo.ac.jp>
  • Date: Thu, 7 Feb 2002 05:12:29 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

All you need is to insert Evaluate on the left hand side.

In[1]:=
mylist={{"a","b","c","d"},{1,23,45,678}}

Out[1]=
{{a,b,c,d},{1,23,45,678}}

In[2]:=
Evaluate[ToExpression[mylist][[1]]]=mylist[[2]];


In[3]:=
{a,b,c,d}

Out[3]=
{1,23,45,678}


On Wednesday, February 6, 2002, at 05:42  PM, Mark Van De Vyver wrote:

> Hi MathGroup,
>
> I'm having trouble with the following variable and data import:
> The import file is input.txt:
>
> a b c d
> 1 23 45 678
>
> inputData=Import[input.txt,"Table"]
> {{a,b,c,d},{1,23,45,678}}
>
> This all works OK.
> Head[..]  indicates the a,b,c and d are strings, which is fine, because
> ToExpression[..] changes them to symbols.  What I'd like to do is use
> inputData to do the following:
>
> {a,b,c,d}={1,23,45,678}
>
> However, if I try
>
> ToExpression[ inputData[[1]] ] = inputData[[2]]
>
> I get an error:
>
> Set::write: Tag ToExpression in ToExpression[a] is Protected.
>
> If I then enter 'a' in Mathematica I do not get 1 returned!  No matter 
> how I try I
> can't work it so that when I enter the symbol 'a' in Mathematica I get 
> the value
> from inputData[[2]].
>
> Not sure if that makes sense?
>
>
>
>
>
Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/



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