Re: LOGO-L> eliminating items randomly from a list

[Chuck Shavit <CShavit@MagicSquare.com>]

Brian Harvey wrote: 
 >   I am beginning to think that what's needed is a new library procedure
 >   called something like EXTRACT:
 > 
 >   to extract :stuff [:index 1+random count :stuff] [:sofar []]
 >   if :index = 1 [output list (first :stuff) (se (reverse :sofar) (bf
:stuff))]
 >   output (extract (bf :stuff) (:index-1) (fput first :stuff :sofar))
 >   end
 >  ? 
 >   What do you all think?

I am a Logo illiterate;  My knowledge of Logo lets me understand the clear
programs of Yehuda, but that's about it.  Every once in a while I read a
question in Logo-L about list manipulation, and am rather amazed at the
replies.  Typically, replies fall in two categories: very long functions,
or two liners (like the one above).  To my eyes they all look
incomprehensible, and maybe too complex for what one tries to achieve.

So my questions to the forum are, can lists be treated as [dynamic] arrays?
 What is the difference between a list and an array?  If they differ, why
is that difference required?

The reason I ask is that if one considers a list as an array, then
accessing one or more contiguous elements can be done with great ease, IMO.
  Operations like extracting or inserting elements could be done even by
non-Gurus.

Chuck Shavit

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