jquery arrays intersect

Question

I previously posted this question as jquery/javascript: arrays - jquery/javascript: arrays. But since I am a complete beginner I have formulated the question wrong and didn't understand the answers either.... :(

After failing to implement the given solutions I did some more looking around I found out that I need to compare 6 arrays of possible choices and intersect them to finally display only the overlapping values.

So this is, hopely, a clearer formulation:

I have 6 questions/6 groups of radio buttons for answers. Each answer has multiple values (they can range from 1 to 38 items to be displayed in final 'advice'). I am collecting the values of checked radios in arrays. I get 6 arrays.

How do I intersect 6 arrays in order to get one final array containing only intersecting values form all 6 choices? How do I turn items of this final array into selectors?

Can someone please help me? Thank you!

My script looks now like:

(function($){
  $.fn.checkboxval = function(){
      var outArr = [];
      this.filter(':checked').each(function(){
            outArr.push(this.getAttribute("value"));
      });
      return outArr;
  };
})
(jQuery);
$(function(){
  $('#link').click(function(){
    var valArr1 = $('#vraag1 input:radio:checked').checkboxval();
    var valArr2 = $('#vraag2 input:radio:checked').checkboxval();
    var valArr3 = $('#vraag3 input:radio:checked').checkboxval();
    var valArr4 = $('#vraag4 input:radio:checked').checkboxval();
    var valArr5 = $('#vraag5 input:radio:checked').checkboxval();
    var valArr6 = $('#vraag6 input:radio:checked').checkboxval();
// var newArray = $.merge(valArr1, valArr2, valArr3, valArr4, valArr5, valArr6); <- test to see if I can merge them
// $('#output').text(newArray.join(',')); <- test to see if I can join them
//$("#output").html($("#output").html().replace(/,/gi, ',#diet')); <- test to see if I can append text so it looks like the selectors of divs I need to display later
//    return false;
  });
});

my form/inputs looks like:

<input name="vraag1" type="radio" value="1a,4,5,12,13,17a,18,19,22,23,24,26,27,28,29,30,33,38,6" class="radio advice" id="vraag1-0" /><label for="vraag1-0">ja</label>
<br />
<input name="vraag1" type="radio" value="1b,1,2,3,7,8,11,9,14,15,16,17,20,21,25,31,34,35,36,37,10,32" class="radio advice" id="vraag1-1" /><label for="vraag1-1">nee</label>
<br />
<input name="vraag1" type="radio" value="1c,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,17a,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38" class="radio advice" id="vraag1-2" /><label for="vraag1-2">maakt mij niet uit</label>

Answer 1

With jQuery loaded, you can punch in the console:

a1=[1,2,3]
a2=[2,3,4,5]
$.map(a1,function(a){return $.inArray(a, a2) < 0 ? null : a;})

The output should be:

[2, 3]

Answer 2

Was just wondering the same thing and came up with this:

$(["a","b"]).filter(["a","c"])

returns

["a"]

Answer 3

If yoou want do do an intersect operation on arrays you can use the jQuery plugin jQuery Array Utilities

Here is an example code line of how to use it:

$.intersect([1, 2, 2, 3], [2, 3, 4, 5, 5])

will return the result [2,3]

Answer 4

Your question is still very confusing to me.

But it appears you are getting the value from the inputs and trying to combine them. But they are all strings not arrays.

Try just adding the strings together, then breaking them apart using split() (demo)

$('#link').click(function() {
    var radios = '';
    $('input:radio:checked').each(function() {
        radios += $(this).val() + ',';
    })
    // remove last comma & convert to array
    radios = radios.substring(0, radios.length - 1).split(',');
    // do something with the array
    console.debug(radios);
})

---

Update: Ok, from your demo HTML, I couldn't get 6 duplicates so in the demo I set it to find 3+ matches. I had to write this script to find duplicates in an array I also made it to return an associative object with the number of duplicates. There may be a better method, but this is what I came up with (updated demo):

$(function() {
    $('#link').click(function() {
        var radios = '';
        $('input:radio:checked').each(function() {
            radios += $(this).val() + ',';
        })
        // remove last comma & convert to array
        var results = [],
            dupes = radios
             .substring(0, radios.length - 1)
             .split(',')
             .getDuplicates(),
            arr = dupes[0],
            arrobj = dupes[1],
            minimumDuplicates = 6; // Change this to set minimum # of dupes to find

        // find duplicates with the minimum # required
        for (var i=0; i < arr.length; i++){
            if ( arrobj[arr[i]] >= minimumDuplicates ){
                results.push(arr[i]);
            }
        }

        // Show id of results
        var diets = $.map(results, function(n,i){ return '#diet' + n; }).join(',');
        $(diets).show(); // you can also slideDown() or fadeIn() here
    })
});


/* Find & return only duplicates from an Array
 * also returned is an object with the # of duplicates found
 * myArray = ["ccc", "aaa", "bbb", "aaa", "aaa", "aaa", "aaa", "bbb"];
 * x = myArray.getDuplicates();
 * // x = [ array of duplicates, associative object with # found]
 * // x = [ ['aaa','bbb'] , { 'aaa' : 5, 'bbb' : 2 } ]
 * alert(x[0]) // x[0] = ['aaa','bbb'] & alerts aaa,bbb
 * alert(x[1]['aaa']) // alerts 5;
 */
Array.prototype.getDuplicates = function(sort) {
    var u = {}, a = [], b = {}, c, i, l = this.length;
    for (i = 0; i < l; ++i) {
        c = this[i];
        if (c in u) {
            if (c in b) { b[c] += 1; } else { a.push(c); b[c] = 2; }
        }
        u[c] = 1;
    }
    // return array and associative array with # found
    return (sort) ? [a.sort(), b] : [a, b];
}

Answer 5

See Simplest code for array intersection in javascript for an intersection function. Split the strings with split(",") and do an intersection on the resulting arrays of strings.

Answer 6

function intersect(a, b) {
    var aIsShorter = a.length < b.length;
    var shorter = aIsShorter ? a : b;
    var longer = aIsShorter ? b : a;

    return longer.filter(isFoundInOther).filter(isFoundOnce);

    function isFoundInOther(e) {
        return shorter.indexOf(e) !== -1;
    }

    function isFoundOnce(element, index, array) {
        return array.indexOf(element) === index;
    }
}