问根据R中的查找值为不同列分配值

#Item scores
item1 <- c(NA, 1, NA, 4)
item2 <- c(NA, 2, NA, 3)
item3 <- c(NA, 3, NA, NA)
item57 <- c(NA, 4, 4, 1)

mydata <- data.frame(item1, item2, item3, item57)

#Lookup values based on item score
lookup <- data.frame(score = 1:4, value=c(6, 7, 8, 10))

#Desired output (adding value that is tied to item score to the original data)
desiredOutput <- cbind(mydata,
                   value1 = c(NA, 6, NA, 10),
                   value2 = c(NA, 7, NA, 8),
                   value3 = c(NA, 8, NA, NA),
                   value57 = c(NA, 10, 10, 6))