R help - Jun 2007 - String manipulation, insert delim

Hello All,

I've been using R for two years now and I am happy to say this is the
first time I could not find the answer to my problem in the R-help
archives. Here is the pending problem:

I want to be able to insert delimiters, say commas, into a string of
characters at uneven intervals such that:

foo<-c("haveaniceday")#my string of character
bar<-c(4,1,4,3) # my vector of uneven intervals

my.fun(foo,bar) # some function that places delimiters appropriately

have,a,nice,day # what the function would ideally return

I've tried multiple for-loops using cut and paste but have not had success.

Thanks!
Chris Marcum
UCI Sociology

Try this:
> paste(read.fwf(textConnection(foo), bar, as.is = TRUE), collapse =
",")
[1] "have,a,nice,day"


On 6/18/07, Christopher Marcum <cmarcum at uci.edu>
wrote:
> Hello All,
>
> I've been using R for two years now and I am happy to say this is the
> first time I could not find the answer to my problem in the R-help
> archives. Here is the pending problem:
>
> I want to be able to insert delimiters, say commas, into a string of
> characters at uneven intervals such that:
>
> foo<-c("haveaniceday")#my string of character
> bar<-c(4,1,4,3) # my vector of uneven intervals
>
> my.fun(foo,bar) # some function that places delimiters appropriately
>
> have,a,nice,day # what the function would ideally return
>
> I've tried multiple for-loops using cut and paste but have not had
success.
>
> Thanks!
> Chris Marcum
> UCI Sociology
>
> ______________________________________________
> R-help at 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.
>

This should work for you.
> foo<-c("haveaniceday")#my string of character
> bar<-c(4,1,4,3) # my vector of uneven intervals
> my.function <- function(foo, bar){
+     # construct a matrix with start/end character positions
+     start <- head(cumsum(c(1, bar)), -1) # delete last one
+     sel <- cbind(start=start,
+                  end=start + bar -1)
+     strings <- apply(sel, 1, function(x) substr(foo, x[1], x[2]))
+     paste(strings, collapse=',')
+ }
>
> my.function(foo, bar)
[1] "have,a,nice,day"
>
>


On 6/18/07, Christopher Marcum <cmarcum@uci.edu>
wrote:
>
> Hello All,
>
> I've been using R for two years now and I am happy to say this is the
> first time I could not find the answer to my problem in the R-help
> archives. Here is the pending problem:
>
> I want to be able to insert delimiters, say commas, into a string of
> characters at uneven intervals such that:
>
> foo<-c("haveaniceday")#my string of character
> bar<-c(4,1,4,3) # my vector of uneven intervals
>
> my.fun(foo,bar) # some function that places delimiters appropriately
>
> have,a,nice,day # what the function would ideally return
>
> I've tried multiple for-loops using cut and paste but have not had
> success.
>
> Thanks!
> Chris Marcum
> UCI Sociology
>
> ______________________________________________
> 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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

	[[alternative HTML version deleted]]

On Mon, 2007-06-18 at 16:54 -0700, Christopher Marcum
wrote:
> Hello All,
> 
> I've been using R for two years now and I am happy to say this is the
> first time I could not find the answer to my problem in the R-help
> archives. Here is the pending problem:
> 
> I want to be able to insert delimiters, say commas, into a string of
> characters at uneven intervals such that:
> 
> foo<-c("haveaniceday")#my string of character
> bar<-c(4,1,4,3) # my vector of uneven intervals
> 
> my.fun(foo,bar) # some function that places delimiters appropriately
> 
> have,a,nice,day # what the function would ideally return
> 
> I've tried multiple for-loops using cut and paste but have not had
success.
> 
> Thanks!
> Chris Marcum
> UCI Sociology
One more variation on the replies already provided:

foo <- c("haveaniceday")
bar <- c(4, 1, 4, 3)

insert.char <- function(x, at, char = ",")
{
   cs.at <- cumsum(at)
   vec <- unlist(strsplit(x, ""))
   for (i in seq(length(cs.at) - 1))
     vec <- append(vec, char, cs.at[i] + i - 1)
   paste(vec, collapse = "")
}

> insert.char(foo, bar)
[1] "have,a,nice,day"

See ?append

HTH,

Marc Schwartz