3 dimensional Array Javascript

Question

I have a string that I am splitting using string.split(' '); in order to turn the string into an array.

suppose I have these two tables, table1 and table2.

<table border="1" id="table1">
    <tr>
        <th colspan="2">Image One</th>
    </tr>
    <tr>
        <td style="width:40%;"><img src="airplane.jpg" alt="Image 1"></td>
        <td>
            <dl>
              <dt>airplane</dt>
              <dt>flight</dt>
              <dt>travel</dt>
              <dt>military</dt>
              <dt>word war</dt>
              <dt>GI</dt>
            </dl>
        </td>
    </tr>
</table>

<table border="1" id="table2">
    <tr>
        <th colspan="2">Image Two</th>
    </tr>
    <tr>
        <td style="width:40%;"><img src="apple.jpg" alt="Image 1"></td>
        <td>
            <dl id="tags">
              <dt>red</dt>
              <dt>apple</dt>
              <dt>round</dt>
              <dt>fruit</dt>
              <dt>healthy</dt>
              <dt>doctor</dt>
            </dl>
        </td>
    </tr>
</table>

right now for testing purposes I have an id of tags on table2's dl.

I am using a function to turn that DL (#tags) into an array

function getArray(id) {
var node, list, arrValue;

    array = [];
    for (node = document.getElementById(id).firstChild;
        node;
        node = node.nextSibling) {
        if (node.nodeType == 1 && node.tagName == 'DT') {
            array.push(node.innerHTML);
        }
    }
    console.log(array)
}

in order to check it against my original string to see if any of the values match. However, I am going to have multiple DT's that the string is going to be check against. Would it be correct to add all the tables into a 3d array and then check the values in the string against the 3d array? or is there a better approach?

UPDATE

The problem is:

I am eventually going to have tables filled with an image and tags. Essentially I want to be able to search those tags against my string (which will be separated into an array) then return the image with the most tags in the string. I am trying to figure out the best way to do that. Thank you

What do you mean by "3d array"? Also, please post your whole dl-to-array function. — Bergi
– Bergi, Commented Dec 19, 2012 at 19:34
so to recap: You are creating an array from a string, then you want to compare those array values with values already in a table on the page? Are you open to using jQuery? — Patrick Gunderson
– Patrick Gunderson, Commented Dec 19, 2012 at 19:34
@Eric: I can not see what you want to do with a 3 dimensional array. Please describe your problem, not what you think the solution would be. — Bergi
– Bergi, Commented Dec 19, 2012 at 19:43
So you have source array ['red', 'sky'] that needs to be checked against arbitrary number of arrays e.g. ['red', 'apple', 'round'], ['airplane', 'flight', 'travel'], ...? I see a 2d array, not 3d. — Salman Arshad
– Salman Arshad, Commented Dec 19, 2012 at 19:56

Alnitak · Accepted Answer · 2012-12-19 19:51:39Z

3

Rather than an array I would use an Object to store the list of tags, where the keys are the tags and the values are irrelevant.

This would give you O(1) lookup to check whether some other string exists in that list, as opposed to an O(n) lookup if you were using array.indexOf().

The function below will find every DT on the page and then return an object containing a map from each DT's text to the ID of its parent DL.

function makeMap() {
    var map = {};
    var dls = document.getElementsByTagName('DL');
    for (var i = 0, n = dls.length; i < n; ++i) {
        var dl = dls[i];
        var id = dl.id;
        var node = dl.firstChild;
        while (node) {
            if (node.nodeType == 1 && node.tagName == 'DT') {
                var tag = node.textContent || node.innerText; // latter for MSIE
                map[tag] = id;
            }
            node = node.nextSibling;
        }
    }
    return map;
}

Alternatively, in jQuery (with some pure JS mixed in for efficiency):

function makeMap2() {
    var map = {};
    var $dt = $('dl > dt');
    $dt.each(function() {
        var tag = this.textContent || this.innerText;
        map[tag] = this.parentNode.id;
    });
    return map;
}

edited Dec 19, 2012 at 19:51

answered Dec 19, 2012 at 19:34

Alnitak

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5 Comments

Bergi Over a year ago

I guess the values should be the table(s) in which the tags are contained, as the OP seems to search for them.

Alnitak Over a year ago

@Bergi if you like, yes, if each tag can only appear in one table then you could use the values to indicate which one.

Eric Goncalves Over a year ago

@Alnitak Could you give an example please?

Eric Goncalves Over a year ago

@Alnitak Thanks for the update, however I am still slightly confused on how to implement it. What value do I give to the 'map' parameter? Also, I Would have to call this for every dl? say there are 100+

Eric Goncalves Over a year ago

@Alnitak how would I view the values?

Bergi · Accepted Answer · 2012-12-19 20:49:32Z

1

You wouldn't use a three-dimensional array, but only a two-dimensional one with tables and their tags. Or, as Alnitak already mentioned, even better a lookup object:

var map = {};
var dls = document.getElementsByTagName('dl');
for (var i = 0, i < dls.length; i++) {
    var tableid = dls[i].id; // identifier?
    var dts = dls[i].getElementsByTagName('dt'); // assuming you don't nest them
    for (var j = 0; j < dts.length; j++) {
        var text = dts[j].textContent || dts[i].innerText;
        var tags = text.split(/\s+/);
        for (var k=0; k<tags.length; k++)
            if (tags[k] in map)
                map[tags[k]].push(tableid);
            else
                map[tags[k]] = [tableid]; // an array
    }
}
/* now, map could look like this:
{
    word: ["table1"],
    war: ["table1"],
    red: ["table2"],
    double: ["table1", "table2"], // tags in more than one table
    …
}
*/

To get the table with the most tags in the string you now can use a function like this, which returns the respective tableids sorted by tag occurence:

function getHighestTables(string) {
    var tags = string.split(/\s+/);
    var tablecounts = {};
    for (var i=0; i<tags.length; i++) {
        var tables = map[tags[i]] || [];
        for (var j=0; j<tables.length; j++) {
            var tableid = tables[j];
            if (tableid in tablecounts)
                tablecounts[tableid]++;
            else
                tablecounts[tableid] = 1;
        }
    }
/*  tablecounts might now look like this:
    {
        table1: 2
        table2: 5
    }
*/
    return Object.keys(tablecounts).sort(function (a, b) {
        return tablecounts[b] - tablecounts[a];
    });
}

edited Dec 19, 2012 at 20:49

answered Dec 19, 2012 at 20:15

Bergi

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6 Comments

Eric Goncalves Over a year ago

Thanks for your input, how would I use this with my html?

Eric Goncalves Over a year ago

I moved everythign over to a jsfiddle jsfiddle.net/J4kF9 if you check the console, I am getting an error

Bergi Over a year ago

Thanks for the hints, I fixed the bugs. Updated to jsfiddle.net/J4kF9/1, and the output says that there are more tags from the sentence found in table2 than in table1

Eric Goncalves Over a year ago

Thank you very much, you helped helped me tremendously

Eric Goncalves Over a year ago

Just out of curiosity how difficult would it be to edit this function for more than 2 tables

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