class AbstractPlotWidget : public QCustomPlot
    {
        Q_OBJECT;

QList<double>
        AbstractPlotWidget::keys()
        {
            QList<double> keyList;

            QCPDataMap *data = graph()->data();

            return data->keys();
        }

QStringList
    AbstractPlotWidget::keysAsStringList()
    {
        QStringList keyStringList;

        QCPDataMap *data = graph()->data();

        QList<double> keyList = data->keys();

        for(int iter = 0; iter < keyList.size(); ++iter)
        {
            double keyValue = keyList.at(iter);

            keyStringList.append(QString("%1n").arg(keyValue));
        }

        return keyStringList;
    }