Hi, guys:

For the following code, how could I extract the "start" position of the match and then calculate the average, which will be (1+5)/2=3?

How could I do this for "A", "C", "G", "T", without writing a loop?

Thank you very much & Best regards, Jie

Average of start values:

> temp = matchPattern("A", "ACGTA", max.mismatch=0)
> vls = start(temp)
> mean(vls)

You will have to loop in some fashion, I would suggest a vapply:

> vapply(X = c("A", "C", "G", "T"), 
 FUN.VALUE  = numeric(1), 
 FUN  = function(dna, stringTomatch){ 
     views = matchPattern(dna, stringTomatch, max.mismatch=0) 
     vls = start(views)
     return(mean(vls))
 }, 
 stringTomatch="ACGTA")


A C G T 
3 2 3 4