[R] interval between specific characters in a string...

[Andrew Hart]

Here's a function that can get the interval sizes for you.

getStringSegmentLengths <- function(s, delim, ...) {
   nchar(unlist(strsplit(s, delim, ...))) + 1L
}

It uses strsplit to return a list of all the segments of the string 
separated by delim. delim can be a regular expression and with ..., you 
can pass all the extra options to strsplit in order to specify how to 
break up the string.
It then uses unlist to convert the list output of strsplit to a 
character vector. nchar then gives the lengths of all the elements of 
the character vector and finally a 1 is added to each of these in order 
to obtain the correct interval sizes.

Hth,
Andrew.

On 2/12/2022 14:18, Evan Cooch wrote:
> Was wondering if there is an 'efficient/elegant' way to do the following 
> (without tidyverse). Take a string
> 
> abaaabbaaaaabaaab
> 
> Its easy enough to count the number of times the character 'b' shows up 
> in the string, but...what I'm looking for is outputing the 'intervals' 
> between occurrences of 'b' (starting the counter at the beginning of the 
> string). So, for the preceding example, 'b' shows up in positions
> 
> 2, 6, 7, 13, 17
> 
> So, the interval data would be: 2, 4, 1, 6, 4
> 
> My main approach has been to simply output positions (say, something 
> like unlist(gregexpr('b', target_string))), and 'do the math' between 
> successive positions. Can anyone suggest a more elegant approach?
> 
> Thanks in advance...
> 
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