new Set(data.map(elem => elem.cluster_size))].sort(
        (a, b) => ((typeof (b) === 'number') - (typeof (a) === 'number')) || (a - b)).map(elem => {
        let selector = document.createElement('a');
        selector.className = 'selector selector-active';
        selector.appendChild(document.createTextNode(elem));
        cluster_sizes.appendChild(selector);
        if (!(elem in selectors.cluster_size)) {
            selectors.cluster_size[elem] = true;
        }
        selector.addEventListener('cl