Hi,
You could also use these:
library(Biostrings)
gregexpr2("AB",new)
#[[1]]
#[1] 4 10 14
length(unlist(gregexpr2("AB",new)))
#[1] 3
length(unlist(gregexpr2("BA",new)))
#[1] 2
matchPattern("AB",new)
# Views on a 16-letter BString subject
#subject: AAAABBBBBABBBABB
#views:
# start end width
#[1] 4 5 2 [AB]
#[2] 10 11 2 [AB]
#[3] 14 15 2 [AB]
res1<-matchPattern("AB",new)
length(res1)
#[1] 3
res2<-matchPattern("BA",new)
length(res2)
#[1] 2
#another string
new1<-c("ABABAAABABAAAABABABBA")
res2<-matchPattern("BA",new1)
length(res2)
#[1] 7
length(unlist(gregexpr2("BA",new1)))
#[1] 7
A.K.
----- Original Message -----
From: rnewbie565 <amy.jacobs...@gmail.com>
To: r-help@r-project.org
Cc:
Sent: Thursday, August 2, 2012 5:27 PM
Subject: [R] text search in r
I am trying to count the number of times that the characters in a string
change
For example-
new=c(AAAABBBBBABBBABB)
I want to find the number of times that B changes to A and the number of
times that A changes to B. I tried the grep command but I only figured out
the positions of when B changes to A when I only need the number of times it
occurs.
--
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
