GribCollection.GroupHcs readGroup(GribCollectionProto.Group p, GribCollection.GroupHcs group)
      throws IOException {

    byte[] rawGds = p.getGds().toByteArray();
    Grib2SectionGridDefinition gdss = new Grib2SectionGridDefinition(rawGds);
    Grib2Gds gds = gdss.getGDS();
    int gdsHash = (p.getGdsHash() != 0) ? p.getGdsHash() : gds.hashCode();
    group.setHorizCoordSystem(gds.makeHorizCoordSys(), rawGds, gdsHash);

    group.varIndex = new ArrayList<GribCollection.VariableIndex>();
    for (int i = 0; i < p.getVariablesCount(); i++)
      group.varIndex.add(readVariable(p.getVariables(i), group));
    Collections.sort(group.varIndex);

    group.timeCoords = new ArrayList<TimeCoord>(p.getTimeCoordsCount());
    for (int i = 0; i < p.getTimeCoordsCount(); i++)
      group.timeCoords.add(readTimeCoord(p.getTimeCoords(i)));

    group.vertCoords = new ArrayList<VertCoord>(p.getVertCoordsCount());
    for (int i = 0; i < p.getVertCoordsCount(); i++)
      group.vertCoords.add(readVertCoord(p.getVertCoords(i)));

    group.ensCoords = new ArrayList<EnsCoord>(p.getEnsCoordsCount());
    for (int i = 0; i < p.getEnsCoordsCount(); i++)
      group.ensCoords.add(readEnsCoord(p.getEnsCoords(i)));

    group.filenose = new int[p.getFilenoCount()];
    for (int i = 0; i < p.getFilenoCount(); i++) group.filenose[i] = p.getFileno(i);

    readTimePartitions(group, p);

    // finish
    for (GribCollection.VariableIndex vi : group.varIndex) {
      TimeCoord tc = group.timeCoords.get(vi.timeIdx);
      vi.ntimes = tc.getSize();
      VertCoord vc = (vi.vertIdx < 0) ? null : group.vertCoords.get(vi.vertIdx);
      vi.nverts = (vc == null) ? 0 : vc.getSize();
      EnsCoord ec = (vi.ensIdx < 0) ? null : group.ensCoords.get(vi.ensIdx);
      vi.nens = (ec == null) ? 0 : ec.getSize();
    }

    // group.assignVertNames();

    return group;
  }
  private boolean createPartitionedTimeCoordinates(TimePartition.Partition canon, Formatter f)
      throws IOException {
    List<TimePartition.Partition> partitions = tp.getPartitions();
    boolean ok = true;

    // for each group in canonical Partition
    for (GribCollection.GroupHcs firstGroup : canon.makeGribCollection(f).getGroups()) {
      String gname = firstGroup.getId();
      if (trace) f.format(" Check Group %s%n", gname);

      // get list of corresponding groups from all the time partition, so we dont have to keep
      // looking it up
      List<PartGroup> pgList = new ArrayList<PartGroup>(partitions.size());
      for (TimePartition.Partition dc : partitions) {
        GribCollection.GroupHcs gg = dc.makeGribCollection(f).findGroupById(gname);
        if (gg == null) logger.error(" Cant find group {} in partition {}", gname, dc.getName());
        else pgList.add(new PartGroup(gg, dc));
      }

      // unique time coordinate unions
      List<TimeCoordUnion> unionList = new ArrayList<TimeCoordUnion>();

      // for each variable in canonical Partition
      for (GribCollection.VariableIndex viCanon : firstGroup.varIndex) {
        if (trace) f.format(" Check variable %s%n", viCanon);
        TimeCoord tcCanon = viCanon.getTimeCoord();

        List<TimeCoord> tcPartitions = new ArrayList<TimeCoord>(pgList.size());

        // for each partition, get the time index
        for (PartGroup pg : pgList) {
          // get corresponding variable
          GribCollection.VariableIndex vi2 = pg.group.findVariableByHash(viCanon.cdmHash);
          if (vi2 == null) { // apparently not in the file
            f.format(
                "   WARN Cant find variable %s in partition %s / %s%n",
                viCanon, pg.tpp.getName(), pg.group.getId());
            tcPartitions.add(null);
          } else {
            if (vi2.timeIdx < 0 || vi2.timeIdx >= pg.group.timeCoords.size()) {
              logger.error(" timeIdx out of range var= {} on partition {}", vi2, pg.tpp.getName());
              tcPartitions.add(null);
            } else {
              TimeCoord tc2 = vi2.getTimeCoord();
              if (tc2.isInterval() != tcCanon.isInterval()) {
                logger.error(
                    " timeIdx wrong interval type var= {} on partition {}", vi2, pg.tpp.getName());
                tcPartitions.add(null);
              } else {
                tcPartitions.add(tc2);
              }
            }
          }
        }

        // union of time coordinates
        TimeCoordUnion union = new TimeCoordUnion(tcCanon.getCode(), tcPartitions, tcCanon);

        // store result in the first group
        viCanon.partTimeCoordIdx =
            TimeCoordUnion.findUnique(unionList, union); // this merges identical TimeCoordUnion
      }

      /* turn TimeIndex into TimeCoord
      for (int tidx = 0; tidx <unionList.size(); tidx++) {
        TimeCoordUnion union = unionList.get(tidx);
        f.format(" %s %d: timeIndexList=", firstGroup.hcs.getName(), tidx);
        for (int idx : union.) f.format("%d,",idx);
        f.format("%n");
      } */

      // store results in first group
      firstGroup.timeCoordPartitions = unionList;
    }

    return ok;
  }
  // consistency check on variables : compare each variable to corresponding one in proto
  // also set the groupno and partno for each partition
  private boolean checkPartitions(TimePartition.Partition canon, Formatter f) throws IOException {
    List<TimePartition.Partition> partitions = tp.getPartitions();
    int npart = partitions.size();
    boolean ok = true;

    // for each group in canonical Partition
    GribCollection canonGc = canon.makeGribCollection(f);
    for (GribCollection.GroupHcs firstGroup : canonGc.getGroups()) {
      String gname = firstGroup.getId();
      if (trace) f.format(" Check Group %s%n", gname);

      // hash proto variables for quick lookup
      Map<Integer, GribCollection.VariableIndex> check =
          new HashMap<Integer, GribCollection.VariableIndex>(firstGroup.varIndex.size());
      List<GribCollection.VariableIndex> varIndexP =
          new ArrayList<GribCollection.VariableIndex>(firstGroup.varIndex.size());
      for (GribCollection.VariableIndex vi : firstGroup.varIndex) {
        TimePartition.VariableIndexPartitioned vip = tp.makeVariableIndexPartitioned(vi, npart);
        varIndexP.add(vip);
        check.put(vi.cdmHash, vip); // replace with its evil twin
      }
      firstGroup.varIndex = varIndexP; // replace with its evil twin

      // for each partition
      for (int partno = 0; partno < npart; partno++) {
        TimePartition.Partition tpp = partitions.get(partno);
        if (trace) f.format(" Check Partition %s%n", tpp.getName());

        // get corresponding group
        GribCollection gc = tpp.makeGribCollection(f);
        int groupIdx = gc.findGroupIdxById(firstGroup.getId());
        if (groupIdx < 0) {
          f.format(" Cant find group %s in partition %s%n", gname, tpp.getName());
          ok = false;
          continue;
        }
        GribCollection.GroupHcs group = gc.getGroup(groupIdx);

        // for each variable in partition group
        for (int varIdx = 0; varIdx < group.varIndex.size(); varIdx++) {
          GribCollection.VariableIndex vi2 = group.varIndex.get(varIdx);
          if (trace) f.format(" Check variable %s%n", vi2);
          int flag = 0;

          GribCollection.VariableIndex vi1 = check.get(vi2.cdmHash); // compare with proto variable
          if (vi1 == null) {
            f.format(
                "   WARN Cant find variable %s from %s in proto - ignoring that variable%n",
                vi2, tpp.getName());
            continue; // we can tolerate this
          }

          // compare vert coordinates
          VertCoord vc1 = vi1.getVertCoord();
          VertCoord vc2 = vi2.getVertCoord();
          if ((vc1 == null) != (vc2 == null)) {
            f.format(
                "   ERR Vert coordinates existence on variable %s in %s doesnt match%n",
                vi2, tpp.getName());
            ok = false;
          } else if ((vc1 != null) && !vc1.equalsData(vc2)) {
            f.format(
                "   WARN Vert coordinates values on variable %s in %s dont match%n",
                vi2, tpp.getName());
            f.format("    canon vc = %s%n", vc1);
            f.format("    this vc = %s%n", vc2);
            flag |= TimePartition.VERT_COORDS_DIFFER;
          }

          // compare ens coordinates
          EnsCoord ec1 = vi1.getEnsCoord();
          EnsCoord ec2 = vi2.getEnsCoord();
          if ((ec1 == null) != (ec2 == null)) {
            f.format(
                "   ERR Ensemble coordinates existence on variable %s in %s doesnt match%n",
                vi2, tpp.getName());
            ok = false;
          } else if ((ec1 != null) && !ec1.equalsData(ec2)) {
            f.format(
                "   WARN Ensemble coordinates values on variable %s in %s dont match%n",
                vi2, tpp.getName());
            f.format("    canon ec = %s%n", ec1);
            f.format("    this ec = %s%n", ec2);
            flag |= TimePartition.ENS_COORDS_DIFFER;
          }

          ((TimePartition.VariableIndexPartitioned) vi1)
              .setPartitionIndex(partno, groupIdx, varIdx, flag);
        } // loop over variable
      } // loop over partition
    } // loop over group

    if (ok) f.format("  Partition check: vert, ens coords OK%n");
    return ok;
  }