@Override
 public double[][] getXYZData(String sector, String x, String y, String z, int t) {
   final double[][] result;
   final SectorDataset sectorDataset = getSectorDataset(sector, t);
   if (sectorDataset == null) {
     result = null;
   } else {
     result = sectorDataset.getXYZData(x, y, z);
   }
   return result;
 }
 @Override
 public List<XYDataItem> getScatterData(String sector, String x, String y, int t, String select) {
   final List<XYDataItem> result;
   final SectorDataset sectorDataset = getSectorDataset(sector, t);
   if (sectorDataset != null) {
     result = sectorDataset.getScatter(x, y, select);
   } else {
     result = null;
   }
   return result;
 }
 @Override
 public Object[][] getData(String sector, String keys, int t, String select) {
   final Object[][] result;
   final SectorDataset sectorDataset = getSectorDataset(sector, t);
   if (sectorDataset != null) {
     result = sectorDataset.getData(keys, select);
   } else {
     result = null;
   }
   return result;
 }
 @Override
 public Double[] getDistributionData(String sector, String key, int t, String select) {
   final Double[] result;
   final SectorDataset sectorDataset = getSectorDataset(sector, t);
   if (sectorDataset != null) {
     result = sectorDataset.getField(key, select);
   } else {
     result = null; // TODO générer une erreur ?
   }
   return result;
 }
 @Override
 public String getMessage(String sector, String agent, String key, int lag) {
   final String result;
   final int t = timer.getPeriod().intValue() - lag;
   final SectorDataset sectorDataset = getSectorDataset(sector, t);
   if (sectorDataset != null) {
     result = sectorDataset.getAgentInfo(agent, key);
   } else {
     result = null; // TODO générer une erreur ?
   }
   return result;
 }