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MathGroup Archive 2007

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Re: Quick Question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg78146] Re: [mg78090] Quick Question
  • From: János <janos.lobb at yale.edu>
  • Date: Sat, 23 Jun 2007 07:25:07 -0400 (EDT)
  • References: <200706221050.GAA16639@smc.vnet.net>

On Jun 22, 2007, at 6:50 AM, rob cronin wrote:

> Quick Question:
>
> With Mathematica 5.2 is there any way to scramble a simple list of 
> numbers:
> i.e. randomly rearange the list {1,2,3,4,5,6} without any apparent 
> order.
>
> Kind regards
>

Here is a newbie approach:

In[1]:=
lst = {1, 2, 3, 4, 5, 6}

From the Help of Union you can take UnsortedUnion

In[4]:=
UnsortedUnion[x_] :=
   Module[{f},
    f[y_] := (f[y] = Sequence[
         ]; y); f /@ x]

Then one scramble might look like :

In[7]:=
rst = UnsortedUnion[
    Table[lst[[Random[Integer,
       {1, Length[lst]}]]],
     {i, 1, Length[lst]*
       Length[lst]}]]
Out[7]=
{4, 6, 2, 3, 5, 1}

If course it is good only if the elements of the starting lst are 
distinct.

J=E1nos


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