[R] Function for finding matching values in two vectors.

arun smartpink111 at yahoo.com
Tue May 28 20:05:37 CEST 2013


Hi,
You could use:
which(a%in%b)
#[1] 1 2 3 4 5

a1<-c(1,2,5)

b1<-c(1,3,4,5,7)
which(a1%in%b1)
#[1] 1 3
A.K.



Hello! I created the following function for calculating which elements 
in vector a are existant in vector b. However, all I get is NA NA NA and I can´t figure out why. =/ 



fun <- function(a, b) { 
  y <- rep(NA, length(a)) 
  x <- 0 
  while (x <= length(b)) { 
    x <- x + 1 
    for (i in 1:length(a)) { 
        y[i]<- (a[i] == b[x]) 
    } 
  } 
  return(y) 
} 

fun(a<-1:5,b<-1:9) 


Thanks for any help!



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