[R] Identifying common prefixes from a vector of words, and delete those prefixes

[Martin Morgan]

Daren Tan <daren76 at hotmail.com> writes:

> For example, c("dog.is.an.animal", "cat.is.an.animal",
> "rat.is.an.animal"). How can I identify the common prefix is
> ".is.an.animal" and delete it to give c("dog", "cat", "rat") ?

The 'Rlibstree' package from omegahat is quite fun for this sort of
thing:

> install.packages('Rlibstree', repos="http://www.omegahat.org/R")
[snip]
> library(Rlibstree)
> rstrings <- function(string) {
+     lapply(lapply(strsplit(string, ""), rev),
+            paste, collapse="")
+ }
> pets <- c("dog.is.an.animal", "cat.is.an.animal", "rat.is.an.animal")
> commonSfx <- rstrings(getCommonPrefix(rstrings(pets)))
> commonSfx
[[1]]
[1] ".is.an.animal"
> sub(commonSfx, "", pets)
[1] "dog" "cat" "rat"

Martin
  
> Thanks
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-- 
Martin Morgan
Computational Biology / Fred Hutchinson Cancer Research Center
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