Re: Is it safe to use join on a hash?

And it seems to work fine

This suggests that you want an array of unique numbers. It would be better to use the "uniq" function of List::Util. This function preserves the original order. Note that I print colons (:) to separate array elements.

use strict;
use warnings;
use List::Util qw(uniq);

my @nums = (17, 10, 20, 33, 30, 40, 10, 33, 40, 15, 16, 17);

my @un_nums = uniq(@nums);

local $" = ":";
print "@un_nums\n";
[download]

OUTPUT:

17:10:20:33:30:40:15:16
[download]

Bill

Comment on Re: Is it safe to use join on a hash? Select or Download Code

Replies are listed 'Best First'.
Re^2: Is it safe to use join on a hash? by syphilis (Archbishop) on Sep 07, 2020 at 04:10 UTC
It would be better to use the "uniq" function of List::Util Beware `List::Util::uniq()` with numbers. There's no problem with the integer values being thrown about in this thread, but `uniq` looks at the stringified values, and there are large numbers of floating point values (including many that represent large integer values) that are unequivalent, yet stringify to the same string: `use warnings; use List::Util qw(uniq uniqnum); $x = sqrt 2.0; # Create $y with a less precise # approximation of sqrt 2 $y = "$x" + 0; #$y != $x print "unequivalent\n" if $x != $y; # But $x and $y both stringify # to 1.4142135623731, hence: $count = uniq($x, $y); print $count; __END__ # Outputs: unequivalent 1` [download] Using `uniqnum` instead of `uniq` yields a value of `2` for `$count` . If you want to weed out duplicate strings, use `uniq` or `uniqstr` . But if you want to safely weed out duplicate numeric values, use `uniqnum` ... and, even then, use only the uniqnum implementation that comes with List::Util-1.55 or later. (Actually, there might be other modules that now implement a `uniqnum` function correctly .... I haven't checked.) Cheers, Rob	[reply] [d/l] [select]
Re^2: Is it safe to use join on a hash? by AnomalousMonk (Archbishop) on Sep 07, 2020 at 02:34 UTC
pritesh_ugrankar: Note that List::Util`::uniq()` will return unique elements in the exact order of the input list (less duplicates, of course); this can be very useful in some cases. A duplicate removal approach like that shown here will return unique elements in random order. Also note that in older (and also in current) versions of Perl, `uniq()` can also be found in the List::MoreUtils module; it has not always lived in List::Util. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]