On Mon, 2008-09-22 at 21:21 -0400, ANJAN PURKAYASTHA wrote: > here is my problem: > i have to check the entries of a column and write them out to a file if they > happen to be DNA sequences ie they are exclusively composed of the letters > A, T, G, C- no spaces or digits. > the column also happens to have other strings that are made of > word/digit/space characters. > i tried > if($x=~ /[ATGC]/ )then ..... > however this pattern matching expression is unable to filter out the non-DNA > sequences. > i have also tried other expressions too convoluted to write out here. > > any ideas?
Your question is not clear. Do you want to write the line if it has a DNA sequence or just the sequence? Are sequences of one letter acceptable? When you column, do you mean they appear vertically in a column when printed in a monospaced font, or is there some other marker that indicates a column? To extract sequences from a line: @sequences = split /[^ATGC]+/, $line; -- Just my 0.00000002 million dollars worth, Shawn Linux is obsolete. -- Andrew Tanenbaum -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/