Apply random class to multiple groups of elements with no repeat

I have multiple groups of divs that I need to apply a random class to with no repeats in each of the groups. Once I've done this, I then need to 'reset' the Array back to the original values, and move onto the next group of divs where I apply a random class to each div again.

The idea is to get to something that looks like this:

<div class="mini-thumbnail-container">
    <div class="mini-thumbnail-individual-image left">
    <div class="mini-thumbnail-individual-image centre">
    <div class="mini-thumbnail-individual-image right">
</div>

<div class="mini-thumbnail-container">
    <div class="mini-thumbnail-individual-image centre">
    <div class="mini-thumbnail-individual-image right">
    <div class="mini-thumbnail-individual-image left">
</div>

<div class="mini-thumbnail-container">
    <div class="mini-thumbnail-individual-image right">
    <div class="mini-thumbnail-individual-image left">
    <div class="mini-thumbnail-individual-image centre">
</div>

etc.

I've shamelessly taken code taken from another stackoverflow question to do with this question, but I can't figure out how to get it to work over all my elements, instead of the first three.

Here's the jQuery:

function shuffle(obj) {
    var l = obj.length,
        i = 0,
        rnd,
        tmp;

    while (i < l) {
        rnd = Math.floor(Math.random() * i);
        tmp = obj[i];
        obj[i] = obj[rnd];
        obj[rnd] = tmp;
        i += 1;
    }
}

var classes = ["centre", "left", "right"];
shuffle(classes);

jQuery(".mini-thumbnail-individual-image").each(function() {
    jQuery(this).addClass(classes.pop());
});

And here's a basic outline of my div structure – I have multiples of these which I want to iterate over and apply the random class to each <div class="mini-thumbnail-individual-image">

HTML:

<div class="col-1-6">
    <div class="mini-thumbnail-container">
        <div class="mini-thumbnail-individual-image">
            <img class="mini-thumbnail-image" src="" />
        </div>
        <div class="mini-thumbnail-individual-image">
            <img class="mini-thumbnail-image" src="" />
        </div>
        <div class="mini-thumbnail-individual-image">
            <img class="mini-thumbnail-image" src="" />
        </div>
    </div>
</div>

I think I need to create a loop that looks is triggered after each iteration over the array, and once it spots the array is empty, I need to push the class names back in, and then loop over the next group of divs, until each group of divs has a random class applied, but maybe there is a simpler way that I haven't thought of yet.

Thanks in advance!