Re: LOGO-L> (turn a list);butitem

[George Mills <mills@softronix.com>]

Once again it depends on if you consider your "list" as a SET or
an ordered LIST. Some applications are interested in what was
randomly removed and some applications are interested in the
original ordered list with just that element removed.

Dreyfuss Pierre-Andre wrote:
> 
> That's right there is a side effect with poprandom and pick&remove, the original
> list is turned.
> If the goal is to continue picking randomly other items, it is not a inconvenient.
> 
> For me turn is a ground piece to build other things with it.
> 
> Here a better turn to use as tool for kids.
> 
> to turn :l [:n 1 + random  count :l]
> repeat  :n [make "l lput first :l bf :l ]
> op :l
> end
> 
> With default it acts just as previous turn, turning randomly; with a value for :n
> it turns the list for :n
> position.
> 
> show (turn [a b c d] 2)
> [c d a b]
> 
> About butitem, what do you thing for that:
> 
> to butitem :n :l
> op filter [not  # = :n]:l
> end
> 
> ; and for butitems
> 
> to butitems :itemlist :l
> op filter [not memberp # :itemlist] :l
> end
> 
> ;  And to be complete,  then add  items.
> 
> to items :itemlist :l
> op filter [memberp # :itemlist] :l
> end
> 
> I like the symetry of items and butitems .
> 
> Regards.
> 
> P-A Dreyfuss
> 
> 
> 
> >That's similar to what my BUTITEM did.
> >It shifted things over until the item you want removed
> >is at the head and pops it off and returns the left and
> >right list.
> >
> >But your solution also has the side effect of changing
> >the order of the list. If I read it correctly.
> >
> >Your solution is clever though.
> >You could rotate the wheel back before you output
> >if the side effect is not desired. Which is by the way
> >what the popping out of the recursive call does.
> >
> >Dreyfuss Pierre-Andre wrote:
> >>
> >> Here is a solution based of the circular shift of the list.
> >>
> >> Make a wheel with your list then turn the wheel an
> >> pick the element at the head.
> >>
> >> to  turn :l
> >> repeat  1 + random count :l [make "l lput first :l bf :l ]
> >> op :l
> >> end
> >>
> >> turn uses only repeat and make which should be in any logo.
> >>
> >> Turn just return the list with random circular permutation.
> >> pick the first element for use and continue with the rest (bf ) of the list.
> >>
> >> ; So build poprandom (If you have pop in library)
> >>
> >> to poprandom :nameoflist
> >> make :nameoflist turn thing :nameoflist
> >> op pop :nameoflist
> >> end
> >>
> >> ; Or the same with basic primitives.
> >>
> >> to pick&remove  :nameoflist
> >> make :nameoflist turn thing :nameoflist
> >> localmake "picked first thing :nameoflist
> >> make  :nameoflist bf thing :nameoflist
> >> op :picked
> >> end
> >>
> >> You can work with first and butfirs.
> >> As in this example.
> >>
> >> to printrandom :l
> >> if emptyp :l [stop]
> >> make "l  turn :l
> >> print first :l
> >> printrandom bf :l
> >> end
> >>
> >> And now your dream :
> >>
> >> to shuffle :l [:l2 []]
> >> if emptyp :l [op :l2]
> >> make "l turn :l
> >> op (shuffle bf  :l  fput first :l  :l2)
> >> end
> >>
> >> Shuffle returns a list with the elements randomly shuffled.
> >>
> >> butitem is a good tool to put in the library
> >>
> >> If you like turn you can find a better name for it,
> >> I don't speak english very well.
> >>
> >> Regards
> >>
> >> P-A Dreyfuss.
> >>
> >> >I hope there is an easy explanation, but I can't find it!  I have tried
> >>
> >> >every combination of likely commands I can think of, to no avail.
> >> >
> >> >I have a list with 11 words in it; each is the name of a procedure.  I am
> >>
> >> >trying to pick one of these words at random and then eliminate it from the
> >>
> >> >list.  (At a certain button click, all of the words can be restored to the
> >>
> >> >list.)  But all I can manage to do is either run through the list in the
> >>
> >> >same order as originally entered, eliminating the first (or last) each time
> >>
> >> >(using butfirst or butlast), or select randomly without eliminating any
> >>
> >> >words and sometimes have the same word get chosen repeatedly.  How can I
> >>
> >> >select a word randomly and then place that word at the beginning or end
> >> of
> >> >the list so it can be eliminated?  Or if this is not possible, is there
> >>
> >> >some handy way of entering the list in a newly scrambled order each time
> >> a
> >> >button is clicked?  Does it help to put the list into a text box?
> >> >
> >> >Thanks in advance,
> >> >Wendy Petti
> >> >Washington International School
> >> >wap3@cornell.edu  or comp3@wis.edu
> >>
> >> >
> >> >
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> >>
> >> >
> >>
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> >--
> >===============================================================
> >George Mills
> >email: mills@softronix.com
> >http://www.softronix.com
> >The www page contains some very powerful educational software.
> >Our single most important investment is our kids.
> >
> 
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> http://www.mailexcite.com
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-- 
===============================================================
George Mills
email: mills@softronix.com
http://www.softronix.com
The www page contains some very powerful educational software.
Our single most important investment is our kids.
---------------------------------------------------------------
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questions about the list administration to logofdn@gsn.org.  To
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