Is the number before, in or after the interval? using spaceship operator <=>

rsFalse has asked for the wisdom of the Perl Monks concerning the following question:

I had a task for myself: given interval and a number, find if it is before, in, or after an interval? It can be find using two basic comparisons. But here I tried to use ternary <=>:

use POSIX;
while(<DATA>){
    chomp;
    ($l, $r)=split/ /;
    printf "[%2d %2d] ", $l, $r;
    for $i(-9..10){
        $i or print "|";
        printf "%2d ", floor (($i - $l ) / ($r - $l +1 )) <=> 0
        }
    print "\n"
    }
__DATA__
1 4
2 5
3 7
0 3
-1 5
-8 -2
[download]

OUTPUT:

[ 1  4] -1 -1 -1 -1 -1 -1 -1 -1 -1 |-1  0  0  0  0  1  1  1  1  1  1 
[ 2  5] -1 -1 -1 -1 -1 -1 -1 -1 -1 |-1 -1  0  0  0  0  1  1  1  1  1 
[ 3  7] -1 -1 -1 -1 -1 -1 -1 -1 -1 |-1 -1 -1  0  0  0  0  0  1  1  1 
[ 0  3] -1 -1 -1 -1 -1 -1 -1 -1 -1 | 0  0  0  0  1  1  1  1  1  1  1 
[-1  5] -1 -1 -1 -1 -1 -1 -1 -1  0 | 0  0  0  0  0  0  1  1  1  1  1 
[-8 -2] -1  0  0  0  0  0  0  0  1 | 1  1  1  1  1  1  1  1  1  1  1
[download]

For example I can use the answer as the index of list of 3 elements:
qw(in after before)[find($left, $right, $n)]

Comment on Is the number before, in or after the interval? using spaceship operator <=> Select or Download Code

Replies are listed 'Best First'.
Re: Is the number before, in or after the interval? using spaceship operator <=> by GrandFather (Saint) on Nov 20, 2014 at 20:16 UTC
So what is the question? Perl is the programming world's equivalent of English	[reply]
Re: Is the number before, in or after the interval? using spaceship operator <=> by LanX (Saint) on Nov 21, 2014 at 02:37 UTC
already combining `($_ <=> $l) + ($_ <=> $r)` gives you more details (abs == 1 when border hit) and you can easily derive any info needed. `DB<62> sub tst { print "$_: ", ($_ <=> $l) + ($_ <=> $r), "\n" } DB<63> ($l,$r)=(1,4) => (1, 4) DB<64> tst() for 0..6 0: -2 1: -1 2: 0 3: 0 4: 1 5: 2 6: 2` [download] if you need to ignore borders try `-($_ < $l) \|\| ($_ > $r)` `DB<79> sub leg { print "$_: ", -($_ < $l) \|\| ($_ > $r) \|\| 0, "\n" } DB<80> leg() for 0..6 0: -1 1: 0 2: 0 3: 0 4: 0 5: 1 6: 1` [download] Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)}	[reply] [d/l] [select]
Re: Is the number before, in or after the interval? using spaceship operator <=> by Anonymous Monk on Nov 21, 2014 at 02:42 UTC
Whatever the question was, here's an answer: `use constant ST => ('-1', ' =', ' 0', ' =', ' 1'); printf ' ' x 8 . "%s\n", join ' ', map sprintf('%2d', $_), -9 .. 10; while (<DATA>) { my ($l, $r) = split; printf "[%2d %2d] %s\n", $l, $r, join ' ', map { (ST)[ ($_ <=> $l) + ($_ <=> $r) + 2 ] } -9 .. 10; } __DATA__ 1 4 2 5 3 7 0 3 -1 5 -8 -2` [download] Output: `-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 [ 1 4] -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 = 0 0 = 1 1 1 1 1 1 [ 2 5] -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 = 0 0 = 1 1 1 1 1 [ 3 7] -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 = 0 0 0 = 1 1 1 [ 0 3] -1 -1 -1 -1 -1 -1 -1 -1 -1 = 0 0 = 1 1 1 1 1 1 1 [-1 5] -1 -1 -1 -1 -1 -1 -1 -1 = 0 0 0 0 0 = 1 1 1 1 1 [-8 -2] -1 = 0 0 0 0 0 = 1 1 1 1 1 1 1 1 1 1 1 1` [download] I don't see why 0 should not be legal. `<=>` is not a ternary operator.	[reply] [d/l] [select]
Re: Is the number before, in or after the interval? using spaceship operator <=> by LanX (Saint) on Nov 21, 2014 at 00:44 UTC
> It can be find using two basic comparisons. Strange, I count 6 operations! :) `floor (($i - $l ) / ($r - $l +1 )) <=> 0 1 2 3 4 5 6` [download] Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)} PS: Please don't post such stuff in SOPW without a clear question, you are keeping others busy moderating that stuff: Tricks belong to Cool Uses For Perl Opinions belong to Meditations	[reply] [d/l]
Re^2: Is the number before, in or after the interval? using spaceship operator <=> by rsFalse (Chaplain) on Nov 21, 2014 at 14:43 UTC
Hm.. yes. And that is simpler solution with two basic comparisons: `map { ("-1", " 0", " 1")[ ($_ >= $l) + ($_ > $r) ] } -9 .. 10;`	[reply] [d/l]
Re^3: Is the number before, in or after the interval? using spaceship operator <=> by LanX (Saint) on Nov 21, 2014 at 15:23 UTC
`($_ > $r) - ($_ < $l)` Should already do (can't test on Android :) update tested! =) `DB<41> sub tst { ($_ > $r) - ($_ < $l) } DB<42> $l=3;$r=6 => 6 DB<43> print tst(),"\t" for 0..9 => "" -1 -1 -1 0 0 0 0 1 1 1` [download] Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)}	[reply] [d/l] [select]

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