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MathGroup Archive 2005

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Re: multiple choice IF condition

  • To: mathgroup at smc.vnet.net
  • Subject: [mg56450] Re: [mg56427] multiple choice IF condition
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Tue, 26 Apr 2005 01:32:50 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

a=0;
Table[
    If[i==3||i==5||i==9||i==18,a=a+i;],
    {i,20}];
a

35

Alternatives:

a=0;
Table[
    If[MemberQ[{3,5,9,18},i],a=a+i;],
    {i,20}];
a

35

a=0;
Table[
    If[Or@@Thread[i=={3,5,9,18}],a=a+i;],
    {i,20}];
a

35

Or define your own function

ClearAll[myIf];
SetAttributes[myIf, HoldAll];
myIf[i_Symbol==Or[val__],t_,f_:Null]:=
    If[Or@@Thread[i=={val}],t,f];

a=0;
Table[
    myIf[i==Or[3,5,9,18],a=a+i;],
    {i,20}];
a

35


Bob Hanlon

> 
> From: marloo3 at mail15.com
To: mathgroup at smc.vnet.net
> Date: 2005/04/25 Mon AM 01:30:41 EDT
> Subject: [mg56450] [mg56427] multiple choice IF condition
> 
> could we have a more practical way than this way of choosing some 
numbers of the 
> choice:
> 
> a = 0;
> Table[If[i == 3 || i == 5 || i == 9 || i==18, a = a + i], {i, 20}]
> 
> ie: i wish if it is possible like this:
> If[i==3 ||5 ||9||18, ...]
> 
> Thanks very much
> mark
> 
> 


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