Replace values in a vector based on another vector
Solution 1:
Try with match
y[match(x, x.lvl)]
Solution 2:
Working with factors might be faster:
xf <- as.factor(x)
y[xf]
Note, that levels(xf) gives you a character vector similar to your x.lvl. Thus, for this method to work, elements of y should correspond to appropriate elements of levels(xf).