for(i in levels(as.factor(test4))){        #loop for all occuring levels
  log1 <- rep(0,nlevels(as.factor(test4))) #create logical vector
  log1 <- as.logical(log1)                 #to store results
  if(is.element(i,test1) == TRUE & is.element(i,test2) == TRUE){
    log1[which(levels(as.factor(test4)) == i)] <- TRUE
  } else{
    log1[which(levels(as.factor(test4)) == i)] <- FALSE
}
#if i is element of test1 and test2 the the corresponding entry
#in log1 becomes TRUE, otherwise FALSE

log1
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE

for(i in levels(as.factor(test4))){
  if(is.element(i,test1) == TRUE & is.element(i,test2) == TRUE){
    print(TRUE)
  } else{
    print(FALSE)
  }
}
[1] FALSE
[1] TRUE
[1] TRUE
[1] TRUE
[1] TRUE
[1] FALSE
[1] FALSE

for(i in levels(as.factor(test3))){
  j <- which(levels(as.factor(test3)) == i)
  print(j)
}
[1] 1
[1] 2
[1] 3
[1] 4
[1] 5
[1] 6
[1] 7

test1 <- c(1,2,3,4,5)
test2 <- c(2,3,4,5,6,7)

test4 <- c(test1, test2)

log1 <- rep(0,nlevels(as.factor(test4)))
log1 <- as.logical(log1)

log1[1] <- is.element(1,test1) == TRUE & is.element(1,test2) == TRUE
log1[2] <- is.element(2,test1) == TRUE & is.element(2,test2) == TRUE
log1[3] <- is.element(3,test1) == TRUE & is.element(3,test2) == TRUE
log1[4] <- is.element(4,test1) == TRUE & is.element(4,test2) == TRUE
log1[5] <- is.element(5,test1) == TRUE & is.element(5,test2) == TRUE
log1[6] <- is.element(6,test1) == TRUE & is.element(6,test2) == TRUE
log1[7] <- is.element(7,test1) == TRUE & is.element(7,test2) == TRUE
log1
[1] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE

for(i in levels(as.factor(test4))){
  log1 <- rep(0,nlevels(as.factor(test4)))
  log1 <- as.logical(log1)
  log1[which(levels(as.factor(test4)) == i)] <- is.element(i,test1) == TRUE & is.element(i,test2) == TRUE
}