perl - How can I use the until function with appropriate way -

i have file want filter that:

##matrix=axtchain 16 91,-114,-31,-123,-114,100,-125,-31,-31,-125,100,-114,-123,-31,-114,91 ##gappenalties=axtchain o=400 e=30 chain 21455232 chr20 14302601 + 37457 14119338 chr22 14786829 + 3573 14759345 1 189     159     123 24      30      22 165     21      20 231     105     0 171     17      19 261     0       2231 222     2       0 253     56      48  chain 164224 chr20 14302601 + 1105938 1125118 chr22 14786829 + 1081744 1100586 8 221     352     334 24      100     112 34      56      56 26      50      47 ……………………. chain 143824 chr20 14302601 + 1105938 1125118 chr22 14786829 + 1081744 1100586 8 

so, briefly,there blocks separated blank line. each block begins line " chain xxxxx " , continues lines numbers. want filter out file , keep blocks chain , number follows greater 3000. wrote following script that:

#!/usr/bin/perl use strict; use warnings; use posix;  $chain = $argv[0];  #it filters chains chains >= 3000. open $chain_file, $chain or die "could not open $chain: $!";  @array; while( $cline = <$chain_file>)  {     #next if /^\s*#/;     chomp $cline;     #my @lines = split (/ /, $cline);     if ($cline =~/^chain/) {         @lines = split (/\s/, $cline);         if ($lines[1] >= 3000) {             #print $lines[1];             #my @lines = split (/ /, $cline);              #print "$cline\n";             push (@array, $cline);         }     }     until ($cline ne ' ') {         push (@array, $cline);     }       foreach (@array) {         print "$_\n";      }     undef(@array); } 

the problem can print headers (chain xxxxx…..) , not numbers follows @ next lines of each block. i'm using until function till find blank line, doesn't work. if me that…. thank in advance, vasilis.

the first problem here ' ' single space, not blank line ("" or '' should fine since you've chomp-ed line.

the second problem that

until ( $cline ne "" ) 

is same as

while ( $cline eq "" ) 

which opposite of need push lines @array.

that said, flip-flop operator more suitable construct you're after:

my @array; while ( <$chain_file> ) {          # using $_ instead of $cline      chomp;      if ( { /^chain\s+(\d+)/ && $1 >= 3000 } .. /^$/ ) {                                     # accumulate lines in @array         push @array, $_;           # false until lhs evaluates true ...     }                              # ... true until rhs evaluates true      else {         ( @array ) {           print $_, "\n";          # print matches         }         @array = ();               # reset/clear out @array     } }