Re: getting the highest value in a simpler way

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Re^2: getting the highest value in a simpler way by redEvo (Novice) on Mar 17, 2011 at 20:59 UTC
I realize this is a very old thread, but I just found it and was wondering about the efficiency of this. I understand you could have a long, complicated expression with no room for if statements, with `[ $x => $y ] -> [ $x <= $y ]` as just a small portion of that expression and the example of `my $highestvalue` is just a simple example. However if you were in a loop, and just wanted to keep overwriting $highestvalue every time you find a higher value, wouldn't it be better to write it this way?: `my $x = 0; foreach $y (@lots_of_values){ $x = $y if $y > $x; } return $x;` [download] Is that just as efficient as writing it this way?: `my $x = 0; foreach $y (@lots_of_values){ $x = [ $x => $y ] -> [ $x <= $y ]; } return $x;` [download] The second way seems overly complicated in this case.	[reply] [d/l] [select]
Re^3: getting the highest value in a simpler way by BrowserUk (Patriarch) on Mar 17, 2011 at 21:18 UTC
Is that just as efficient as writing it this way?: Actually, yours is close to 10x more efficient. There is no merit to the 'cute' method beyond it cuteness. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^4: getting the highest value in a simpler way by cLive ;-) (Prior) on Apr 18, 2011 at 12:48 UTC
It makes for a damn good interview question. Asking someone to explain it tells you a lot about how deeply they understand several concepts in Perl. So there's another use :D	[reply]
Re^2: getting the highest value in a simpler way by parv (Parson) on Nov 11, 2004 at 04:31 UTC
...which is same as `$max = $x <= $y ? $y : $x;` and w/o dereferencing. (No, i did not benchmark.)	[reply] [d/l]
Re^2: getting the highest value in a simpler way by uksza (Canon) on Dec 19, 2004 at 02:31 UTC
Hello! `$highestvalue = [ $x => $y ] -> [ $x <= $y ]` [download] Anybody can explanin me this code? I'm a bit confused ;-) Uksza	[reply] [d/l]
Re^3: getting the highest value in a simpler way by BrowserUk (Patriarch) on Dec 19, 2004 at 03:07 UTC
`[ $x => $y ]` is the same as `[ $x, $y ]` which is the essentially the same as `my $ary = ( $x, $y ); my $aryRef = \ @ary;` [download] And `$x <= $y` is just a boolean expression that will give a false (0) result if `$x > $y` and true value (1) otherwise. `$aryRef->[ 0/1 ]` will return either `$ary[ 0 ]` or `$ary[ 1 ]`. Putting it all together, you get an expression that will construct an anonymous array containing `$x, $y`, then dereferences that anonmous array and uses the boolean result of the comparison to select the greater of the two values before assigning it to the scalar. Examine what is said, not who speaks. The end of an era! "But you should never overestimate the ingenuity of the sceptics to come up with a counter-argument." -Myles Allen "Think for yourself!" - Abigail "Time is a poor substitute for thought"--theorbtwo "Efficiency is intelligent laziness." -David Dunham "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon	[reply] [d/l] [select]
Re^4: getting the highest value in a simpler way by uksza (Canon) on Dec 19, 2004 at 15:34 UTC
Hey! I understand!! ;-) So, in exmaple: `my $x = 5 my $y = 10 my $highestvalue = [ $x => $y ] -> [ $x <= $y ] #we have @aray(5,10) and because (5 <= 10) it returns 1, so $highestvalue = aray[1] thats mean 10 in this example, right?` [download] Eh, nice trick... ;-) Thanks for you reply. Uksza	[reply] [d/l]


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