Re: [R] About grep
Shao wrote: Hi,everyone. I have a problem when using the grep. for example: a - c(aa,aba,abac) b- c(ab,aba) I want to match the whole word,so grep(^aba$,a) it returns 2 but when I used it a more useful way: grep(^b[2]$,a), it doesn't work at all, it can't find it, returning integer(0). How can I chang the format in the second way? Thanks. The regexp ^b[2]$ matches only two words: b2 and b (in your present grep call with defaults extended = TRUE, perl = FALSE, fixed = FALSE). They don't present in a, that's why grep returns integer(0). If you want to find the word b[2] (the expression similar to an array indexing operator), either use fixed=TRUE and remove any regexp markup (^ and $) a- c(aa,aba,abac,b[2]) grep(b[2],a,fixed=TRUE) [1] 4 , or use escapes grep(^b\\[2\\]$,a) [1] 4 -- View this message in context: http://www.nabble.com/About-grep-tf4228021.html#a12029243 Sent from the R help mailing list archive at Nabble.com. __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] About grep
On 07-Aug-07 04:20:27, Shao wrote: Hi,everyone. I have a problem when using the grep. for example: a - c(aa,aba,abac) b- c(ab,aba) I want to match the whole word,so grep(^aba$,a) it returns 2 but when I used it a more useful way: grep(^b[2]$,a), it doesn't work at all, it can't find it, returning integer(0). How can I chang the format in the second way? Thanks. -- Shao The problem is that in the string ^b[2]$ the element b[2] of b is not evaluated, but simply the successive characters ^ b [ 2 ] $ are passed to grep as a character string, which of course is not found. You can construct a character string with the value of b[2] in it by using paste(): grep(paste(^,b[2],$,sep=),a) [1] 2 Ted. E-Mail: (Ted Harding) [EMAIL PROTECTED] Fax-to-email: +44 (0)870 094 0861 Date: 07-Aug-07 Time: 07:43:14 -- XFMail -- __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] About grep
Hi,everyone. I have a problem when using the grep. for example: a - c(aa,aba,abac) b- c(ab,aba) I want to match the whole word,so grep(^aba$,a) it returns 2 but when I used it a more useful way: grep(^b[2]$,a), it doesn't work at all, it can't find it, returning integer(0). How can I chang the format in the second way? Thanks. -- Shao [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] About grep
try grep(paste(^,b[2],$,sep=),a) your version will match b2: grep(^b[2]$,c(b,b2,b3)) [1] 2 --- Shao [EMAIL PROTECTED] wrote: Hi,everyone. I have a problem when using the grep. for example: a - c(aa,aba,abac) b- c(ab,aba) I want to match the whole word,so grep(^aba$,a) it returns 2 but when I used it a more useful way: grep(^b[2]$,a), it doesn't work at all, it can't find it, returning integer(0). How can I chang the format in the second way? Thanks. -- Shao [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Pinpoint customers who are looking for what you sell. __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] About grep
Oh,great. Thanks. On 8/7/07, Stephen Tucker [EMAIL PROTECTED] wrote: try grep(paste(^,b[2],$,sep=),a) your version will match b2: grep(^b[2]$,c(b,b2,b3)) [1] 2 --- Shao [EMAIL PROTECTED] wrote: Hi,everyone. I have a problem when using the grep. for example: a - c(aa,aba,abac) b- c(ab,aba) I want to match the whole word,so grep(^aba$,a) it returns 2 but when I used it a more useful way: grep(^b[2]$,a), it doesn't work at all, it can't find it, returning integer(0). How can I chang the format in the second way? Thanks. -- Shao [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Pinpoint customers who are looking for what you sell. http://searchmarketing.yahoo.com/ -- Shao [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
