counting strings ending with a in dataset

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

hi monks please help me in applying this properly , i need the total number of strings ending with A in the dataset

   #!/usr/bin/perl -w
   use strict;
   open DATA , "<GSE_out" or die "Can't open the file $!";
   my @output = <DATA>;
   my $count_A = 0 ;
  close DATA ;
foreach my $line (@output)
 {
    my $length = length ($line);
   
     if (substr($line, 0,$length) eq 'A')
     {
         $count_A++;
     }
  print $count_A++;
[download]

here is the data set

>2
AAAAAAAAACAAAAGAACGAAGAAGT
>3
AAAAAAAAACAACCGAAAAATAGAAAC
>4
AAAAAAAAACAAGAAGGACTAGACC
>7
AAAAAAAAACAAGGACTGGTTTATCAG
>8
AAAAAAAAACAAGTTTCTCTGTGACT
>12
AAAAAAAAACACAGACGTAGAATTGT
>14
AAAAAAAAACACGACCGTTCGCTTTGA
>15
AAAAAAAAACACGACTGTTCGCTTT
>16
AAAAAAAAACACTATGAGCCAGAAC
[download]

Comment on counting strings ending with a in dataset Select or Download Code

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Re: counting strings ending with a in dataset by davido (Cardinal) on Feb 29, 2012 at 06:37 UTC
use strict; use warnings; my $count_A = 0; while ( my $line = <DATA> ) { next if $line =~ m/^>/; # This line probably unnecessary if your d +ata set is as well-behaved as it looks. $count_A++ if $line =~ m/A$/; } print "$count_A\n"; __DATA__ >2 AAAAAAAAACAAAAGAACGAAGAAGT >3 AAAAAAAAACAACCGAAAAATAGAAAC >4 AAAAAAAAACAAGAAGGACTAGACC >7 AAAAAAAAACAAGGACTGGTTTATCAG >8 AAAAAAAAACAAGTTTCTCTGTGACT >12 AAAAAAAAACACAGACGTAGAATTGT >14 AAAAAAAAACACGACCGTTCGCTTTGA >15 AAAAAAAAACACGACTGTTCGCTTT >16 AAAAAAAAACACTATGAGCCAGAAC [download] Dave	[reply] [d/l]
Re^2: counting strings ending with a in dataset by MVRS (Acolyte) on Feb 29, 2012 at 06:52 UTC
thankyou dave its quite simple	[reply]
Re: counting strings ending with a in dataset by JavaFan (Canon) on Feb 29, 2012 at 07:35 UTC
No need to reinvent the wheel with a Perl program, `grep` can do the job: `grep -c 'A$' GSE_out` [download]	[reply] [d/l] [select]
Re: counting strings ending with a in dataset by locked_user sundialsvc4 (Abbot) on Feb 29, 2012 at 18:56 UTC
There’s an important distinction between davido’s solution and yours. You “slurped” the entire file into memory; David read it line-by-line. Most of the time, you want to do it David’s way because otherwise you’re doing a great big file-copy ... from a disk file, to the virtual-memory file! You almost never want to do that.