Re: add letters to the begin of the sentence

This technique should do what you want:

$ perl -Mstrict -Mwarnings -e '
    my @fasta = (">dddd\n", "abcdef\n", ">eeee\n", "bcdef\n");

    for (@fasta) {
        print "aaaa" unless /^>/;
        print;
    }
'
>dddd
aaaaabcdef
>eeee
aaaabcdef
[download]

Using your filehandles, that would be:

while (<$input_fh>) {
    print $output_fh 'aaaa' unless /^>/;
    print $output_fh $_;
}
[download]

If the ACGAGTGCGT in your code is supposed to be the aaaa in your description, then just make the appropriate substitution. If it isn't, a clarification would be useful.

-- Ken

Comment on Re: add letters to the begin of the sentence Select or Download Code

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Re^2: add letters to the begin of the sentence by intect (Initiate) on Sep 13, 2013 at 13:18 UTC
Thank you, Ken. It works very well. Would you help me identify the problem in my script. I moved the print after unless block but it still does not work.	[reply]
Re^3: add letters to the begin of the sentence by kcott (Archbishop) on Sep 13, 2013 at 19:03 UTC
"Thank you, Ken. It works very well." You're welcome. "Would you help me identify the problem in my script." Happy to. "I moved the print after unless block but it still does not work." Unfortunately, that doesn't help me to help you. What exactly did you move? Where precisely did you move it to? What does "it still does not work" mean? You need to provide code along with expected results, actual results, and any error or warnings messages. This is all described in more detail in the "How do I post a question effectively?" guidelines. Here's what choroba was referring to: `$ perl -Mstrict -Mwarnings -e ' my @fasta = (">dddd\n", "abcdef\n", ">eeee\n", "bcdef\n"); for (@fasta) { unless (/^>/) { s/^/ACGAGTGCGT/; } print; } ' >dddd ACGAGTGCGTabcdef >eeee ACGAGTGCGTbcdef` [download] That may give you your answer. If not, post the requested information so that we can provide genuine help as opposed to guesswork. -- Ken	[reply] [d/l]