var data = [];

var numOfPoints = 3;
var numOfTraces = 6;
var bargap = 0.4;

var categories = [];

for (p = 0; p < numOfPoints; p++) {
    categories.push("cat " + p);
}

for (var t = 0; t < numOfTraces; t++) {
    var values = [];
    for (p = 0; p < numOfPoints; p++) {
        values.push(Math.round((Math.random() - 0.5) * 100));
    }
    var trace = {
        x: categories,
        y: values,
        type: "bar",
        name: "Series " + t
    }

    data.push(trace);
}

var annotations = [];
var delta = (1 - bargap) / numOfTraces;
var pivot = Math.floor(numOfTraces / 2);

for (var i = 0; i < categories.length; i++) {
    for (var j = 0; j < data.length; j++) {
        var offset = j - pivot;
        if ((numOfTraces % 2) === 0) {
            offset += 0.5;
        }
        var x = i + offset * delta;
        var y = data[j].y[i];
        var a = {
            x: x,
            y: y,
            text: y,
            xanchor: 'center',
            yanchor: y >= 0 ? 'bottom' : 'top',
            showarrow: false
        };
        annotations.push(a);
    }
}

var layout = {
    barmode: 'group',
    bargroupgap: 0.02,
    bargap: bargap,
    annotations: annotations
};

Plotly.newPlot('myDiv', data, layout);