I have a two part question
Part 1)
I am trying to remove characters in a string based on the position of a key
character in another string. I have a solution that works but it requires a
for-loop. A vectorized way of doing this has alluded me.
CleanRead<-function(x,y) {
if (!is.character(x))
x <- as.character(x)
if (!is.character(y))
y <- as.character(y)
idx<-grep("\\*", x, value=FALSE)
starpos<-gregexpr("\\*", x[idx])
ysplit<-strsplit(y[idx], '')
n<-length(idx)
for(i in 1:n) {
ysplit[[i]][starpos[[i]]] = ""
}
y[idx]<-unlist(lapply(ysplit, paste, sep='', collapse=''))
return(y)
}
x<-c("AA*.*A,,,", "**a.a*,,,A", "C*c..", "**aA")
y<-c("abcdefghi", "abcdefghij", "abcde", "abcd")
CleanRead(x,y)
[1] "abdfghi" "cdeghij" "acde" "cd"
Is there a better way to do this?
Part 2)
My next step in the string processing is to take the characters in the output
of CleanRead and subtract 33 from the ascii value of the character to obtain an
integer. Again I have a solution that works, involving splitting the string
into characters then converting them to factors (starting at ascii 34) and
using unclass to get the integer value. (kindof a atoi(x)-33 all in one step)
I looked for the C equivalent of atoi, but the only help I could find (R-help
2003) suggested using as.numeric. However, the help file (and testing) shows
you get 'NA'.
Am I missing an easier way to do this?
Thanks in advance,
Brian
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