function prepare_data(n, d) {
var tmp = d.slice(0,n);
var out = []
for (var t=0; t<n; t++) {
out.push({"key": tmp[t].name, "values":[], "selector": tmp[t].name.replace(/[^A-Za-z0-9]/g,'').replace(/ /g,'')})
}
for (var date=1; date<40; date++) {
var ranks = tmp.map(x => +x[date]);
var indices = sorted_idx(ranks);
for (var i = 0; i < indices.length; i++) {
out[indices[i]].values.push({"date":date, "rank":i})
}
}
return out;
}