On Wed, Feb 8, 2012 at 12:33 PM, Yang, Joy (NIH/NHGRI) [F] <joy.y...@nih.gov> wrote: > Hi, > > Is there a way to efficiently replace specified indices in a string with > another character? For example, if I had a vector of strings such as > > [1] "hellohowareyoudoing" > [2] "imgoodhowareyou" > [3] "goodandyou" > [4] "yesimgoodijusttoldyou" > [5] "ohyesthatsright" > > and had a list of positions that I want to replace with the character "-" > > [[1]] > [1] 3 9 > > [[2]] > [1] 3 4 > > [[3]] > [1] 4 7 > > [[4]] > [1] 5 6 7 8 9 > > [[5]] > [1] 2 5 7 12 > > I would like to get > > [1] "he-lohow-reyoudoing" > [2] "im--odhowareyou" > [3] "goo-an-you" > [4] "yesi-----ijusttoldyou" > [5] "o-ye-t-atsr-ght" > > Is there an easy way to do this? Or would the easiest way be writing a > function to take substrings of the original vector and pasting in the > replacement character? >
Using this input: pos <- list(c(3, 9), c(3, 4)) s <- c("hellohowareyoudoing", "imgoodhowareyou") we can use regmatches like this where the lapply on the LHS constructs a matches list and the lapply on the RHS constructs a list of "-" characters: f <- function(p) structure(p, match.length = rep(1, length(p))) regmatches(s, lapply(pos, f)) <- lapply(pos, function(p) "-") The resulting s is: > s [1] "he-lohow-reyoudoing" "im--odhowareyou" -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-help@r-project.org 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.