i need to buid a json array just like

 var data1 = [
  [3, 0],
  [15, 90],
  [18, 180],
  [15, 270],
  [12, 0],
  [9, 120],
  [10, 90],
  [18, 30],
  [20, 150],
  [21, 120],
  [18, 100],
  [15, 240],
  [12, 270],
  [9, 120],
  [10, 90],
  [18, 30],
  [3, 150],
  [15, 120],
  [18, 100],
  [15, 240],
  [12, 270],
  [9, 120],
  [10, 90],
  [18, 30],
];

i can build a simple oneline array by using QJsonArray,like this

QString CTestDataModel::ParseToJsonArray(std::vector<double> input)
{
    QJsonArray jsonArray;
    QJsonDocument jsonDoc;
    QByteArray byteArray;

    if (input.empty())
    {
        return QString(" ");
    }

    for (double num:input)
    {
        jsonArray.append(num);
    }
    jsonDoc.setArray(jsonArray);
    byteArray = jsonDoc.toJson(QJsonDocument::Compact);

    QString jsonResult(byteArray);
    return jsonResult;
}

result will be like

var data1= [2500, 1800, 1200, 1600, 3000, 4000, 3500, 2200, 2500, 1800, 1200, 1600, 3000, 4200, 3500, 2200, 2500, 1800, 1200, 1600, 3000, 4000, 3500, 2200];

but it's not what i want,how can i build a 2d js array by use QJsonArray in at5