Creating a pair of arrays from an array resulting in circular array

Question

I am trying to make a function that takes an array and creates a pair of arrays for example an array [1,2,3,4] the pair will be:

pair = [[1, 2], [1, 3], [1, 4], [2, 3], [2, 4], [3, 4]] ;

And the pairs would be:

pairs = [[[1,2],[1,3]], [[1,2],[1,4]], [[1,2],[2,3]] .... [[2,4],[3,4] ] ;

So far my function looks like this:

function makePairs(arr) {

    var l = arr.length -1 ,  
    pair =  [];
        for(var i=0; i < l ; i++ ) {
          for(var j=i+1; j <= l ; j++ ) {
            pair.push( [arr[i],arr[j]]) ;
          }
        }  

  // i get the desired pair by the above nested for loop... 
  // console.log(pair) ; 

  // i try to do the same nested for loop with the pair array.. 
  // but i get [circular object Array]; 
  var k =  pair.length -1,
  pairs = [] ;
          for(var m=0; m < k ; m++ ) {
          for(var n=m+1; n <= k ; n++ ) {
            pairs.push( [pair[m],pair[n]]) ;
          }
        }
    return pairs; 
}

console.log(  makePairs([1,2,3,4]) );

So the pair gives me the desired pair but when I do the same type of nested for loop with the pair array, I get [circular object Array]. I thought the nested for loop will work on the pairs too but it does not. I read that circular reference is formed between a javascript object and a native object causing memory leak but I don't know if that's happening here. please help.

error..

It also runs fine in Chrome. And runs ok in IE, other than the fact that IE flattens the arrays when it logs it. — Scott Mermelstein, Oct 17 '13 at 20:17
@PsychHalf Please post your output as an edit to the question rather than have us look at the appended advertising on the link. Where are you running your code that you're getting the circular object reference? — Scott Mermelstein, Oct 17 '13 at 20:25

score 1 · Accepted Answer · answered Oct 17 '13 at 20:33

1

I wonder if the issue is the debugger itself. It's outputting [circular object Array] any time it's referring to an item already referred to.

Try making a lot more console messages. Replace your last line with:

var answer = makePairs([1,2,3,4]);
for (var i = 0; i < answer.length; ++i) {
    console.log("[[" + answer[i][0][0] + ", " + answer[i][0][1] + "], [" + 
         answer[i][1][0] + ", " + answer[i][1][1] + "]]");
}

I bet it will print out ok.

answered Oct 17 '13 at 20:33

Scott Mermelstein

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@PsychHalf Don't feel stupid - your code was fine, and everyone always trusts their debuggers. What debugger are you using? – Scott Mermelstein Oct 17 '13 at 20:40
thanks... umm.. well.. whatever it was i won't be using it again.. i'm throwing it out of my window right away.. – Psych Half Oct 17 '13 at 20:47
@PsychHalf Not to be too pushy, but was it developer tools with a specific web browser like IE's or Chrome's F12 utilities, or a plugin like FireBug Lite, or something else? It would be good to know "Hey, don't be surprised if you see this error when using this specific tool." – Scott Mermelstein Oct 17 '13 at 20:50
1

try any web based console.. like jsconsole.. or others.. they'all give you circular.. – Psych Half Oct 17 '13 at 21:03

score 0 · Answer 2 · answered Oct 17 '13 at 20:17

0

maybe you can make use of

console.dir(  makePairs([1,2,3,4])  )

on chrome-console and latesst ff-firebug

answered Oct 17 '13 at 20:17

john Smith

17,409
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score 0 · Answer 3 · answered Jun 07 '22 at 06:11

0

Try with JSON.stringify() and JSON.parse() like below:

console.log(
  makePairs(
    JSON.parse(
      JSON.stringify([1,2,3,4])
    )
  )
);

answered Jun 07 '22 at 06:11

itsazzad

6,868
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Creating a pair of arrays from an array resulting in circular array

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