[R] what is wrong with my quicksort?

[Mark Leeds]

hi: the link i sent presents a data example and steps through it with
beautiful figures for
each step.  why don't you take their data example,. use it in your code and put
browser() at the top if your partition function so you can step using n.

your steps should result in EXACTLY the same steps given in the link.
this way you can see what's happening with a working example.





On Sun, Sep 4, 2011 at 4:08 PM, warc <conny-clauss at gmx.de> wrote:
> Hey again and thanks for all the help
>
> this is what i have for now but it still doesn't work, the main problem is
> the random pivot i think
> (error in while (x[j] >= pivot) { : Argument has length 0)
>
>>partition <- function(x, links, rechts){
>>
>>       i <- links
>>       j <- rechts
>>       t <- 0
>>       pivot <- x[sample((links:rechts),1)]
>>
>>
>>       while(i <= j){
>>
>>               while(x[i] <= pivot){
>>                      i = i+1}
>>
>>               while(x[j] >= pivot){
>>                       j = j-1}
>>
>>               if( i <= j){
>>
>>
>>                       t = x[i]
>>                       x[i] = x[j]
>>                       x[j] = t
>>
>>                       i=i+1
>>                       j=j-1
>>
>>                       }
>>               }
>>               return(pivot)
>>               }
>>
>>qsort <- function(x, links, rechts){
>>
>>       index <- partition(x, links, rechts)
>>
>>       if((links < (index+1))&(length(x)>1)){
>>               qsort(x, links, index+1)}
>>
>>
>>       if((index < rechts)&(length(x)>1)){
>>               qsort(x, index, rechts)}
>>
>>       return(x)
>>       }
>>
>>
>>quicksort <- function(x){
>>
>>               if(length(x) == 0)stop("empty Vector")
>>
>>               qsort(x, 1, length(x))
>>}
>
>
>
> but whatever
> i will just keep on trying
>
> thank you again
>
> --
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>
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