Question

In R programming

# given a numeric vector x, and a string vector 'labels' of the
# same length as x, return the vector containing the labels that
# correspond to the k smallest values in vector x.
#
# example:
# if x      = c(3.1, 2.3, 0.1, 4.2) and
#    labels = c("a", "b", "c", "d") and
#    k = 2
# then smallest_labels(x, labels, k) should return c("c", "b")
smallest_labels = function(x, labels, k) {

# YOUR CODE HERE (2)


# HINT: R function 'order' is very handy for this

}

Answer 1

• Inside the function we could bind x, labels into a dataframe in a ordered manner usind order()
• the second row and first k columns of the dataframe contains the k labels will smallest x, access these elements and return it.

function:

smallest_labels = function(x, labels, k) {

ii <- order(x, label);
smallest <- c(rbind(x,label)[,ii][2,1:k])
return(smallest)
}

sample output:

• Let's test the function with sample data in the question

smallest_labels = function(x, labels, k) {

ii <- order(x, label);
smallest <- c(rbind(x,label)[,ii][2,1:k])
return(smallest)
}

x <- c(3.1, 2.3, 0.1, 4.2)
label <- c("a", "b", "c", "d")
k <- 2
print(smallest_labels(x, label, k))

output: