Perl: series of numbers to range notation

Question

I have this series of numbers:

349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,
373,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,
425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,447,448,
449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471,472,
473,474,475,476,477,478,479,480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496

there are two ranges in there: 349-396, 425-496. Any hints as to how to write a perl code to represent the series of numbers as a range?

Comments

(349..396,425..496);

Answer 1

simply looping through the range in numerical order, checking if the number you're looking at is one higher than the last, and either adding it to the "current" range if so, or starting a new range if not, should be pretty easy - e.g. assuming @nums contains that sorted list of numbers, then:

my @ranges;
my @current_range;
my $lastnum;

for my $num (@nums) {
 # See if we're starting a new range - if so, add the last range 
 # to the set of ranges we've found:
 if (@current_range &
 @current_range = ($num);
 # Otherwise, just add this number to the current range
 } else {
 push @current_range, $num;
 }

 $lastnum = $num;
}

# Finally, when we've run out of numbers, we might have a remaining
range left # to add, so handle that:
if (@current_range) {
 push @ranges, (@current_range > 1)
 ? $current_range[0] . '-' . $current_range[-1]
 : @current_range;
}

There are likely shorter and more elegant ways than the above, though.

Answer 2

perl -wE'
 my $csv = q{
 1, 2, 4, 5, 6, 8, 9, 10,
 349,350,351,352,353,354,355,356,357,358,
 359,360,361,362,363,364,365,366,367,368,
 369,370,371,372,373,374,375,376,377,378,
 379,380,381,382,383,384,385,386,387,388,
 389,390,391,392,393,394,395,396,425,426,
 427,428,429,430,431,432,433,434,435,436,
 437,438,439,440,441,442,443,444,445,446,
 447,448,449,450,451,452,453,454,455,456,
 457,458,459,460,461,462,463,464,465,466,
 467,468,469,470,471,472,473,474,475,476,
 477,478,479,480,481,482,483,484,485,486,
 487,488,489,490,491,492,493,494,495,496
 };

 (my $ssr = $csv) =~ s/[^d,]//ga;
 1 while $ssr =~ s/b(d+),(d+)b/($1==$2-1)?"$1-$2":"$1;$2"/e;
 $ssr =~ s/-d+(?=-)//g;

 say $ssr;
'
1-2;4-6;8-10;349-396;425-496
(made for unsigned numbers)