Bubble sort using R language? - r

Question

I am new in programming, and I just start learning R language. I am trying to do a bubble sort, but it shows the following error message. Can anyone help me solve the problem?
x <-sample(1:100,10)
n <- length(x)
example <- function(x)
{
for (i in 1:n-1)
{
while (x[i] > x[i+1])
{
temp <- x[i+1]
x[i+1] <- x[i]
x[i] <- temp
}
i <- i+1
}
}
example(x)
Error in while (x[i] > x[i + 1]) { : argument is of length zero

Answer 1

x<-sample(1:100,10)
example <- function(x){
n<-length(x)
for(j in 1:(n-1)){
for(i in 1:(n-j)){
if(x[i]>x[i+1]){
temp<-x[i]
x[i]<-x[i+1]
x[i+1]<-temp
}
}
}
return(x)
}
res<-example(x)
#input
x
#output
res
It is working fine with little modification of your code. In 'R' it is better to use sort() function.
x <-sample(1:100,10)
x
res<-sort(x)
res

Answer 2

You have some inaccuracies in your algorithm of sorting. I've made changes to make it work.
set.seed(1)
x <-sample(1:100,10)
x
# [1] 27 37 57 89 20 86 97 62 58 6
example <- function(x)
{
n <- length(x) # better insert this line inside the sorting function
for (k in n:2) # every iteration of the outer loop bubbles the maximum element
# of the array to the end
{
i <- 1
while (i < k) # i is the index for nested loop, no need to do i < n
# because passing j iterations of the for loop already
# places j maximum elements to the last j positions
{
if (x[i] > x[i+1]) # if the element is greater than the next one we change them
{
temp <- x[i+1]
x[i+1] <- x[i]
x[i] <- temp
}
i <- i+1 # moving to the next element
}
}
x # returning sorted x (the last evaluated value inside the body
# of the function is returned), we can also write return(x)
}
example(x)
# [1] 6 20 27 37 57 58 62 86 89 97
BTW, R language has a lot of functions and methods for doing things. This example function can be a learning example, but I advice to use existing function sort for solving real problems.
In R language you should try to avoid loops and make usage of vectorized functions to make the code faster.

Answer 3

It gives you that error message because he cannot compare a value that is out of his bounds which is the case for you at (x[i] > x[i + 1]). Try this if you want to sort your array in a decreasing order:
for (i in 1:n){
j = i
while((j>1)){
if ((X[j]> X[j-1])){
temp = X[j]
X[j] = X[j-1]
X[j-1] = temp
}
j = j-1
}
}
For an increasing order you just have to switch around the > sign in the while loop.