[R] corresponding replicated el of one matrix in another matrix or vector

[arun]

Try:
rbind(v2,unname(setNames(v1[,1],v1[,2])[v2]))
   [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13] [,14]
v2 "a"  "a"  "a"  "a"  "a"  "c"  "c"  "c"  "c"  "c"   "c"   "c"   "c"   "c"  
   "1"  "1"  "1"  "1"  "1"  "3"  "3"  "3"  "3"  "3"   "3"   "3"   "3"   "3"  
   [,15] [,16] [,17] [,18]
v2 "c"   "b"   "b"   "b"  
   "3"   "2"   "2"   "2"  
A.K.



Hi,
I have a matrix of unique elements (strings) like v1 and a vector which contains replicated values of the 2nd column of the first matrix.

v1 = cbind(c("1","2","3"),c("a","b","c"))

v2 = c(rep("a",5), rep("c",10), rep("b",3))

How can I add a column to v2 that contains the values of the first column of the first matrix v1 where the 2nd column of v1 matches the values of v2? Do I need to grep by looping over the nrow of v1 which is very time consuming or is there a better solution?

the results should be the same as


v3=rbind( c(rep("a",5), rep("c",10), rep("b",3)), c(rep("1",5), rep("3",10), rep("2",3)))

---------------------------------------------------------------
v1
     [,1] [,2] [,3]
[1,] "1"  "2"  "3"
[2,] "a"  "b"  "c"
> v2
 [1] "a" "a" "a" "a" "a" "c" "c" "c" "c" "c" "c" "c" "c" "c" "c" "b" "b" "b"
> v3
     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13] [,14]
[1,] "a"  "a"  "a"  "a"  "a"  "c"  "c"  "c"  "c"  "c"   "c"   "c"   "c"   "c" 
[2,] "1"  "1"  "1"  "1"  "1"  "3"  "3"  "3"  "3"  "3"   "3"   "3"   "3"   "3" 
     [,15] [,16] [,17] [,18]
[1,] "c"   "b"   "b"   "b" 
[2,] "3"   "2"   "2"   "2"