# String extraction **URL:** \ **Category:** Ruby\ **Created:** [January 10, 2008, 9:38pm UTC](https://www.ruby-forum.com/t/string-extraction/125639 "2008-01-10T21:38:39Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 9:38pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/1 "2008-01-10T21:38:39Z")
Hi all, What is the Ruby way to extract a string like this? old\_string=“5’-AAAAAAAA CCCCCCCC TTT GGGGG GGGG-3’” new\_string=“AAAAAAAACCCCCCCCTTTGGGGGGGGG” Thank you very much, Li ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 9:47pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/2 "2008-01-10T21:47:13Z")
On Jan 10, 2:38 pm, Li Chen [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > – > Posted viahttp://www.ruby-forum.com/. new\_string = old\_string.gsub(/[^A-Z]/, ‘’) That substitutes ‘’ (empty string) for any character that is not (^) a capital letter (A-Z). To do the same thing in place: old\_string.gsub!(/^A-Z]/, ‘’) ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 9:49pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/3 "2008-01-10T21:49:36Z")
Hi – On 10/01/2008, Li Chen [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Hi all, > > What is the Ruby way to extract a string like this? > > old\_string=“5’-AAAAAAAA CCCCCCCC TTT GGGGG GGGG-3’” > new\_string=“AAAAAAAACCCCCCCCTTTGGGGGGGGG” old\_string=“5’-AAAAAAAA CCCCCCCC TTT GGGGG GGGG-3’”.scan(/[A-Z]+/).to\_s And variations thereof. – Thomas A. ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 9:50pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/4 "2008-01-10T21:50:10Z")
yermej wrote: > On Jan 10, 2:38?pm, Li Chen [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > – > > Posted viahttp://www.ruby-forum.com/. > > new\_string = old\_string.gsub(/[^A-Z]/, ‘’) > > That substitutes ‘’ (empty string) for any character that is not (^) a > capital letter (A-Z). > > To do the same thing in place: old\_string.gsub!(/^A-Z]/, ‘’) Thank you so much. Li ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 9:52pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/5 "2008-01-10T21:52:35Z")
Li Chen wrote: > What is the Ruby way to extract a string like this? > > old\_string=“5’-AAAAAAAA Â Â CCCCCCCC Â TTT Â GGGGG Â Â GGGG-3’” > new\_string=“AAAAAAAACCCCCCCCTTTGGGGGGGGG” new\_string = old\_string.gsub(/[^ACTG]/i,"") This removes anything that is not an A, C, T or G (case insensitively. If you want lower case chars acgt to be removed, too, remove the i from the regex). HTH, Sebastian ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 10:03pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/6 "2008-01-10T22:03:03Z")
yermej wrote: > On Jan 10, 2:38?pm, Li Chen [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > – > > Posted viahttp://www.ruby-forum.com/. > > new\_string = old\_string.gsub(/[^A-Z]/, ‘’) > > That substitutes ‘’ (empty string) for any character that is not (^) a > capital letter (A-Z). > > To do the same thing in place: old\_string.gsub!(/^A-Z]/, ‘’) Hi yermej, One more question: How do I change all the As into T and all the Ts into A in the old sttring? old\_s=“AAATTAA” new\_s=“TTTAATT” thanks, Li ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 10:22pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/7 "2008-01-10T22:22:54Z")
Sebastian H. wrote: > Li Chen wrote: > > > How do I change all the As into T and all the Ts into > > A in the old sttring? > > > > old\_s=“AAATTAA” > > new\_s=“TTTAATT” > > new\_s = old\_s.tr(“AT”, “TA”) > or if you also want GC > new\_s = old\_s.tr(“ATGC”, “TACG”) Thank you very much, Li ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 10:30pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/8 "2008-01-10T22:30:12Z")
On Jan 10, 2008, at 2:38 PM, Li Chen wrote: > Hi all, > > What is the Ruby way to extract a string like this? > > old\_string=“5’-AAAAAAAA CCCCCCCC TTT GGGGG GGGG-3’” “5’-AAAAAAAA CCCCCCCC TTT GGGGG GGGG-3’”.delete("^ACTG") James Edward G. II ---
**Author:** ![alex-osu3](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/13edae/32.png) [@alex-osu3](https://www.ruby-forum.com/u/alex-osu3)\ **Post date:** [January 10, 2008, 10:09pm UTC](https://www.ruby-forum.com/t/string-extraction/125639/9 "2008-01-10T22:09:03Z")
Li Chen wrote: > How do I change all the As into T and all the Ts into > A in the old sttring? > > old\_s=“AAATTAA” > new\_s=“TTTAATT” new\_s = old\_s.tr(“AT”, “TA”) or if you also want GC new\_s = old\_s.tr(“ATGC”, “TACG”)