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Re: Getting rid of those deprecated Do[] loops?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg92794] Re: Getting rid of those deprecated Do[] loops?
  • From: "David Park" <djmpark at comcast.net>
  • Date: Mon, 13 Oct 2008 06:20:46 -0400 (EDT)
  • References: <gcsctj$8mj$1@smc.vnet.net>

data = Flatten[Table[{aa, bb, xx, yy}, {aa, 1, 2}, {bb, 10, 30, 10}],
   1];
Print[data // TableForm];

And for more iterators, say filling in xx and yy also:

data =
  Flatten[
   Table[{aa, bb, xx, yy}, {aa, 1, 2}, {bb, {a, b}}, {xx, {1, 2}}, {yy, {c, 
d}}], 3];
data // TableForm

-- 
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/


"AES" <siegman at stanford.edu> wrote in message 
news:gcsctj$8mj$1 at smc.vnet.net...
> Trying to think of a "two-variable iterator" approach that will let one
> produce the same results as
>
> data = { };
> Do[
>   Do[
>      data = AppendTo[data, {aa, bb, xx, yy}],
>      {bb, 10, 30, 10}],
>   {aa, 1, 2}];
> Print[data // TableForm];
>
> without using those universally deprecated (and even worse, nested)
> Do[ ] loops, not to mention the equally deprecated AppendTo[].
>
> Somewhat to my surprise, the construction
>
> Table[{aa = kk[[1]];  bb = kk[[2]];  aa, bb, xx, yy},
>          {kk,  {{1, 10},  {1, 20},  {1, 30},  {2, 10},  {2, 20},
> {2,30}}}
>          ] // TableForm
>
> using a two-dimensional iterator iterator variable kk, actually does
> this, though the "iterator list" is obviously a bit messy.
>
> Simpler way of defining an iterator to do this?  In more than two
> iterator dimensions (aa, bb, cc,...)?  (with no functional dependence
> between the values of aa, bb, cc).
>
> Is the concept of a multi-dimensional iterator variable kk mentioned in
> the M6 documentation anywhere?  (A search on "Iterate" or "iteration"
> brings up 193 hits at 10 per screen.)
> 



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