Re: Array problem

#! perl -slw
use strict;
use List::Util qw[ shuffle ];

my  @start = qw[
    dog cat bird mouse rat snake horse cow
    pig lizard lamb zebra lion elephant monkey
];

my  @want = map{ 
    join ' ', $start[ $_ ], 
    ( shuffle @start[ 0 .. $_-1, $_+1 .. $#start ] )[ 0 .. 2 ] 
} 0 .. $#start;

print for @want;
__END__
dog cat lamb lizard
cat lamb mouse pig
bird pig monkey lizard
mouse bird pig snake
rat dog bird lion
snake mouse horse rat
horse lion elephant lamb
cow lamb horse bird
pig cat rat bird
lizard bird horse cat
lamb rat zebra dog
zebra monkey horse snake
lion pig zebra dog
elephant lamb monkey cow
monkey rat lamb snake
[download]

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

Comment on Re: Array problem Download Code

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Re^2: Array problem by ikegami (Patriarch) on Sep 27, 2008 at 08:06 UTC
A slight alternative is to shuffle the indexes. `my @want = map{ "@start[ $_, ( shuffle 0 .. $_-1, $_+1 .. $#start )[ 0 .. 2 ] ]" } 0 .. $#start;` [download] Don't even need `join` anymore!	[reply] [d/l] [select]
Re^3: Array problem by JavaFan (Canon) on Sep 27, 2008 at 09:54 UTC
But neither are a good solution if the array is large: for each element, you're shuffling (almost) the entire array, just to get three elements. It makes for a quadratic solution, where a linear will do.	[reply]
Re^4: Array problem by BrowserUk (Patriarch) on Sep 27, 2008 at 13:49 UTC
where a linear will do. Could you show us that please? Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^5: Array problem by JavaFan (Canon) on Sep 28, 2008 at 20:09 UTC
Re^6: Array problem by BrowserUk (Patriarch) on Sep 29, 2008 at 00:06 UTC
Some notes below your chosen depth have not been shown here
Re^2: Array problem by AnomalousMonk (Archbishop) on Sep 27, 2008 at 07:30 UTC
Nice, very nice! And a lot better than my effort, which I won't bother to post having seen BrowserUK's; and more than being nice code, it has the additional quality that the the OPer will, I think, hesitate to turn it in for his homework assignment without doing a lot of digging to figure out just what is going on inside this little gem.	[reply]