JAL-2110 added alignAsSameSequences to handle 'direct' (copy) case
[jalview.git] / src / jalview / analysis / AlignmentUtils.java
index fba023f..17aab15 100644 (file)
@@ -22,8 +22,10 @@ package jalview.analysis;
 
 import static jalview.io.gff.GffConstants.CLINICAL_SIGNIFICANCE;
 
+import jalview.api.DBRefEntryI;
 import jalview.datamodel.AlignedCodon;
 import jalview.datamodel.AlignedCodonFrame;
+import jalview.datamodel.AlignedCodonFrame.SequenceToSequenceMapping;
 import jalview.datamodel.Alignment;
 import jalview.datamodel.AlignmentAnnotation;
 import jalview.datamodel.AlignmentI;
@@ -38,6 +40,7 @@ import jalview.io.gff.SequenceOntologyFactory;
 import jalview.io.gff.SequenceOntologyI;
 import jalview.schemes.ResidueProperties;
 import jalview.util.Comparison;
+import jalview.util.DBRefUtils;
 import jalview.util.MapList;
 import jalview.util.MappingUtils;
 import jalview.util.StringUtils;
@@ -849,6 +852,11 @@ public class AlignmentUtils
    */
   public static int alignProteinAsDna(AlignmentI protein, AlignmentI dna)
   {
+    if (protein.isNucleotide() || !dna.isNucleotide())
+    {
+      System.err.println("Wrong alignment type in alignProteinAsDna");
+      return 0;
+    }
     List<SequenceI> unmappedProtein = new ArrayList<SequenceI>();
     Map<AlignedCodon, Map<SequenceI, AlignedCodon>> alignedCodons = buildCodonColumnsMap(
             protein, dna, unmappedProtein);
@@ -856,6 +864,162 @@ public class AlignmentUtils
   }
 
   /**
+   * Realigns the given dna to match the alignment of the protein, using codon
+   * mappings to translate aligned peptide positions to codons.
+   * 
+   * @param dna
+   *          the alignment whose sequences are realigned by this method
+   * @param protein
+   *          the protein alignment whose alignment we are 'copying'
+   * @return the number of sequences that were realigned
+   */
+  public static int alignCdsAsProtein(AlignmentI dna, AlignmentI protein)
+  {
+    if (protein.isNucleotide() || !dna.isNucleotide())
+    {
+      System.err.println("Wrong alignment type in alignProteinAsDna");
+      return 0;
+    }
+    // todo: implement this
+    List<AlignedCodonFrame> mappings = protein.getCodonFrames();
+    int alignedCount = 0;
+    for (SequenceI dnaSeq : dna.getSequences())
+    {
+      if (alignCdsSequenceAsProtein(dnaSeq, protein, mappings,
+              dna.getGapCharacter()))
+      {
+        alignedCount++;
+      }
+    }
+    return alignedCount;
+  }
+
+  /**
+   * Helper method to align (if possible) the dna sequence to match the
+   * alignment of a mapped protein sequence. This is currently limited to
+   * handling coding sequence only.
+   * 
+   * @param cdsSeq
+   * @param protein
+   * @param mappings
+   * @param gapChar
+   * @return
+   */
+  static boolean alignCdsSequenceAsProtein(SequenceI cdsSeq,
+          AlignmentI protein, List<AlignedCodonFrame> mappings, char gapChar)
+  {
+    SequenceI cdsDss = cdsSeq.getDatasetSequence();
+    if (cdsDss == null)
+    {
+      System.err
+              .println("alignCdsSequenceAsProtein needs aligned sequence!");
+      return false;
+    }
+    
+    List<AlignedCodonFrame> dnaMappings = MappingUtils
+            .findMappingsForSequence(cdsSeq, mappings);
+    for (AlignedCodonFrame mapping : dnaMappings)
+    {
+      SequenceI peptide = mapping.findAlignedSequence(cdsSeq, protein);
+      int peptideLength = peptide.getLength();
+      if (peptide != null)
+      {
+        Mapping map = mapping.getMappingBetween(cdsSeq, peptide);
+        if (map != null)
+        {
+          MapList mapList = map.getMap();
+          if (map.getTo() == peptide.getDatasetSequence())
+          {
+            mapList = mapList.getInverse();
+          }
+          int cdsLength = cdsDss.getLength();
+          int mappedFromLength = MappingUtils.getLength(mapList
+                  .getFromRanges());
+          int mappedToLength = MappingUtils
+                  .getLength(mapList.getToRanges());
+          boolean addStopCodon = (cdsLength == mappedFromLength * 3 + 3)
+                  || (peptide.getDatasetSequence().getLength() == mappedFromLength - 1);
+          if (cdsLength != mappedToLength && !addStopCodon)
+          {
+            System.err
+                    .println(String
+                            .format("Can't align cds as protein (length mismatch %d/%d): %s",
+                                    cdsLength, mappedToLength,
+                                    cdsSeq.getName()));
+          }
+
+          /*
+           * pre-fill the aligned cds sequence with gaps
+           */
+          char[] alignedCds = new char[peptideLength * 3
+                  + (addStopCodon ? 3 : 0)];
+          Arrays.fill(alignedCds, gapChar);
+
+          /*
+           * walk over the aligned peptide sequence and insert mapped 
+           * codons for residues in the aligned cds sequence 
+           */
+          char[] alignedPeptide = peptide.getSequence();
+          char[] nucleotides = cdsDss.getSequence();
+          int copiedBases = 0;
+          int cdsStart = cdsDss.getStart();
+          int proteinPos = peptide.getStart() - 1;
+          int cdsCol = 0;
+          for (char residue : alignedPeptide)
+          {
+            if (Comparison.isGap(residue))
+            {
+              cdsCol += 3;
+            }
+            else
+            {
+              proteinPos++;
+              int[] codon = mapList.locateInTo(proteinPos, proteinPos);
+              if (codon == null)
+              {
+                // e.g. incomplete start codon, X in peptide
+                cdsCol += 3;
+              }
+              else
+              {
+                for (int j = codon[0]; j <= codon[1]; j++)
+                {
+                  char mappedBase = nucleotides[j - cdsStart];
+                  alignedCds[cdsCol++] = mappedBase;
+                  copiedBases++;
+                }
+              }
+            }
+          }
+
+          /*
+           * append stop codon if not mapped from protein,
+           * closing it up to the end of the mapped sequence
+           */
+          if (copiedBases == nucleotides.length - 3)
+          {
+            for (int i = alignedCds.length - 1; i >= 0; i--)
+            {
+              if (!Comparison.isGap(alignedCds[i]))
+              {
+                cdsCol = i + 1; // gap just after end of sequence
+                break;
+              }
+            }
+            for (int i = nucleotides.length - 3; i < nucleotides.length; i++)
+            {
+              alignedCds[cdsCol++] = nucleotides[i];
+            }
+          }
+          cdsSeq.setSequence(new String(alignedCds));
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  /**
    * Builds a map whose key is an aligned codon position (3 alignment column
    * numbers base 0), and whose value is a map from protein sequence to each
    * protein's peptide residue for that codon. The map generates an ordering of
@@ -1332,15 +1496,19 @@ public class AlignmentUtils
           Collection<String> types, List<SequenceI> forSequences,
           boolean anyType, boolean doShow)
   {
-    for (AlignmentAnnotation aa : al.getAlignmentAnnotation())
+    AlignmentAnnotation[] anns = al.getAlignmentAnnotation();
+    if (anns != null)
     {
-      if (anyType || types.contains(aa.label))
+      for (AlignmentAnnotation aa : anns)
       {
-        if ((aa.sequenceRef != null)
-                && (forSequences == null || forSequences
-                        .contains(aa.sequenceRef)))
+        if (anyType || types.contains(aa.label))
         {
-          aa.visible = doShow;
+          if ((aa.sequenceRef != null)
+                  && (forSequences == null || forSequences
+                          .contains(aa.sequenceRef)))
+          {
+            aa.visible = doShow;
+          }
         }
       }
     }
@@ -1399,75 +1567,272 @@ public class AlignmentUtils
    * added to the alignment dataset.
    * 
    * @param dna
-   *          aligned dna sequences
-   * @param mappings
-   *          from dna to protein
-   * @param al
+   *          aligned nucleotide (dna or cds) sequences
+   * @param dataset
+   *          the alignment dataset the sequences belong to
+   * @param products
+   *          (optional) to restrict results to CDS that map to specified
+   *          protein products
    * @return an alignment whose sequences are the cds-only parts of the dna
    *         sequences (or null if no mappings are found)
    */
   public static AlignmentI makeCdsAlignment(SequenceI[] dna,
-          List<AlignedCodonFrame> mappings, AlignmentI al)
+          AlignmentI dataset, SequenceI[] products)
   {
+    if (dataset == null || dataset.getDataset() != null)
+    {
+      throw new IllegalArgumentException(
+              "IMPLEMENTATION ERROR: dataset.getDataset() must be null!");
+    }
+    List<SequenceI> foundSeqs = new ArrayList<SequenceI>();
     List<SequenceI> cdsSeqs = new ArrayList<SequenceI>();
-    
-    for (SequenceI seq : dna)
+    List<AlignedCodonFrame> mappings = dataset.getCodonFrames();
+    HashSet<SequenceI> productSeqs = null;
+    if (products != null)
     {
-      AlignedCodonFrame cdsMappings = new AlignedCodonFrame();
+      productSeqs = new HashSet<SequenceI>();
+      for (SequenceI seq : products)
+      {
+        productSeqs.add(seq.getDatasetSequence() == null ? seq : seq
+                .getDatasetSequence());
+      }
+    }
+
+    /*
+     * Construct CDS sequences from mappings on the alignment dataset.
+     * The logic is:
+     * - find the protein product(s) mapped to from each dna sequence
+     * - if the mapping covers the whole dna sequence (give or take start/stop
+     *   codon), take the dna as the CDS sequence
+     * - else search dataset mappings for a suitable dna sequence, i.e. one
+     *   whose whole sequence is mapped to the protein 
+     * - if no sequence found, construct one from the dna sequence and mapping
+     *   (and add it to dataset so it is found if this is repeated)
+     */
+    for (SequenceI dnaSeq : dna)
+    {
+      SequenceI dnaDss = dnaSeq.getDatasetSequence() == null ? dnaSeq
+              : dnaSeq.getDatasetSequence();
+
       List<AlignedCodonFrame> seqMappings = MappingUtils
-              .findMappingsForSequence(seq, mappings);
-      List<AlignedCodonFrame> alignmentMappings = al.getCodonFrames();
+              .findMappingsForSequence(dnaSeq, mappings);
       for (AlignedCodonFrame mapping : seqMappings)
       {
-        for (Mapping aMapping : mapping.getMappingsFromSequence(seq))
+        List<Mapping> mappingsFromSequence = mapping
+                .getMappingsFromSequence(dnaSeq);
+
+        for (Mapping aMapping : mappingsFromSequence)
         {
-          SequenceI cdsSeq = makeCdsSequence(seq.getDatasetSequence(),
-                  aMapping);
+          MapList mapList = aMapping.getMap();
+          if (mapList.getFromRatio() == 1)
+          {
+            /*
+             * not a dna-to-protein mapping (likely dna-to-cds)
+             */
+            continue;
+          }
+
+          /*
+           * skip if mapping is not to one of the target set of proteins
+           */
+          SequenceI proteinProduct = aMapping.getTo();
+          if (productSeqs != null && !productSeqs.contains(proteinProduct))
+          {
+            continue;
+          }
+
+          /*
+           * try to locate the CDS from the dataset mappings;
+           * guard against duplicate results (for the case that protein has
+           * dbrefs to both dna and cds sequences)
+           */
+          SequenceI cdsSeq = findCdsForProtein(mappings, dnaSeq,
+                  seqMappings, aMapping);
+          if (cdsSeq != null)
+          {
+            if (!foundSeqs.contains(cdsSeq))
+            {
+              foundSeqs.add(cdsSeq);
+              SequenceI derivedSequence = cdsSeq.deriveSequence();
+              cdsSeqs.add(derivedSequence);
+              if (!dataset.getSequences().contains(cdsSeq))
+              {
+                dataset.addSequence(cdsSeq);
+              }
+            }
+            continue;
+          }
+
+          /*
+           * didn't find mapped CDS sequence - construct it and add
+           * its dataset sequence to the dataset
+           */
+          cdsSeq = makeCdsSequence(dnaSeq.getDatasetSequence(), aMapping);
+          SequenceI cdsSeqDss = cdsSeq.createDatasetSequence();
           cdsSeqs.add(cdsSeq);
-    
+          if (!dataset.getSequences().contains(cdsSeqDss))
+          {
+            dataset.addSequence(cdsSeqDss);
+          }
+
           /*
            * add a mapping from CDS to the (unchanged) mapped to range
            */
           List<int[]> cdsRange = Collections.singletonList(new int[] { 1,
               cdsSeq.getLength() });
-          MapList map = new MapList(cdsRange, aMapping.getMap()
-                  .getToRanges(), aMapping.getMap().getFromRatio(),
-                  aMapping.getMap().getToRatio());
-          cdsMappings.addMap(cdsSeq, aMapping.getTo(), map);
+          MapList cdsToProteinMap = new MapList(cdsRange, mapList.getToRanges(),
+                  mapList.getFromRatio(), mapList.getToRatio());
+          AlignedCodonFrame cdsToProteinMapping = new AlignedCodonFrame();
+          cdsToProteinMapping.addMap(cdsSeq, proteinProduct, cdsToProteinMap);
+
+          /*
+           * guard against duplicating the mapping if repeating this action
+           */
+          if (!mappings.contains(cdsToProteinMapping))
+          {
+            mappings.add(cdsToProteinMapping);
+          }
+
+          /*
+           * copy protein's dbrefs to CDS sequence
+           * this enables Get Cross-References from CDS alignment
+           */
+          DBRefEntry[] proteinRefs = DBRefUtils.selectDbRefs(false,
+                  proteinProduct.getDBRefs());
+          if (proteinRefs != null)
+          {
+            for (DBRefEntry ref : proteinRefs)
+            {
+              DBRefEntry cdsToProteinRef = new DBRefEntry(ref);
+              cdsToProteinRef.setMap(new Mapping(proteinProduct,
+                      cdsToProteinMap));
+              cdsSeqDss.addDBRef(cdsToProteinRef);
+            }
+          }
 
           /*
            * add another mapping from original 'from' range to CDS
            */
-          map = new MapList(aMapping.getMap().getFromRanges(), cdsRange, 1,
+          AlignedCodonFrame dnaToCdsMapping = new AlignedCodonFrame();
+          MapList dnaToCdsMap = new MapList(mapList.getFromRanges(),
+                  cdsRange, 1,
                   1);
-          cdsMappings.addMap(seq.getDatasetSequence(), cdsSeq, map);
+          dnaToCdsMapping.addMap(dnaSeq.getDatasetSequence(), cdsSeq,
+                  dnaToCdsMap);
+          if (!mappings.contains(dnaToCdsMapping))
+          {
+            mappings.add(dnaToCdsMapping);
+          }
 
-          alignmentMappings.add(cdsMappings);
+          /*
+           * add DBRef with mapping from protein to CDS
+           * (this enables Get Cross-References from protein alignment)
+           * This is tricky because we can't have two DBRefs with the
+           * same source and accession, so need a different accession for
+           * the CDS from the dna sequence
+           */
+          DBRefEntryI dnaRef = dnaDss.getSourceDBRef();
+          if (dnaRef != null)
+          {
+            // assuming cds version same as dna ?!?
+            DBRefEntry proteinToCdsRef = new DBRefEntry(dnaRef.getSource(),
+                    dnaRef.getVersion(), cdsSeq.getName());
+            proteinToCdsRef.setMap(new Mapping(cdsSeqDss, cdsToProteinMap
+                    .getInverse()));
+            proteinProduct.addDBRef(proteinToCdsRef);
+          }
 
           /*
            * transfer any features on dna that overlap the CDS
            */
-          transferFeatures(seq, cdsSeq, map, null, SequenceOntologyI.CDS);
+          transferFeatures(dnaSeq, cdsSeq, cdsToProteinMap, null,
+                  SequenceOntologyI.CDS);
         }
       }
     }
 
+    AlignmentI cds = new Alignment(cdsSeqs.toArray(new SequenceI[cdsSeqs
+            .size()]));
+    cds.setDataset(dataset);
+
+    return cds;
+  }
+
+  /**
+   * A helper method that finds a CDS sequence in the alignment dataset that is
+   * mapped to the given protein sequence, and either is, or has a mapping from,
+   * the given dna sequence.
+   * 
+   * @param mappings
+   *          set of all mappings on the dataset
+   * @param dnaSeq
+   *          a dna (or cds) sequence we are searching from
+   * @param seqMappings
+   *          the set of mappings involving dnaSeq
+   * @param aMapping
+   *          an initial candidate from seqMappings
+   * @return
+   */
+  static SequenceI findCdsForProtein(List<AlignedCodonFrame> mappings,
+          SequenceI dnaSeq, List<AlignedCodonFrame> seqMappings,
+          Mapping aMapping)
+  {
     /*
-     * add CDS seqs to shared dataset
+     * TODO a better dna-cds-protein mapping data representation to allow easy
+     * navigation; until then this clunky looping around lists of mappings
      */
-    Alignment dataset = al.getDataset();
-    for (SequenceI seq : cdsSeqs)
+    SequenceI seqDss = dnaSeq.getDatasetSequence() == null ? dnaSeq
+            : dnaSeq.getDatasetSequence();
+    SequenceI proteinProduct = aMapping.getTo();
+
+    /*
+     * is this mapping from the whole dna sequence (i.e. CDS)?
+     * allowing for possible stop codon on dna but not peptide
+     */
+    int mappedFromLength = MappingUtils.getLength(aMapping.getMap()
+            .getFromRanges());
+    int dnaLength = seqDss.getLength();
+    if (mappedFromLength == dnaLength || mappedFromLength == dnaLength - 3)
     {
-      if (!dataset.getSequences().contains(seq.getDatasetSequence()))
+      return seqDss;
+    }
+
+    /*
+     * looks like we found the dna-to-protein mapping; search for the
+     * corresponding cds-to-protein mapping
+     */
+    List<AlignedCodonFrame> mappingsToPeptide = MappingUtils
+            .findMappingsForSequence(proteinProduct, mappings);
+    for (AlignedCodonFrame acf : mappingsToPeptide)
+    {
+      for (SequenceToSequenceMapping map : acf.getMappings())
       {
-        dataset.addSequence(seq.getDatasetSequence());
+        Mapping mapping = map.getMapping();
+        if (mapping != aMapping && mapping.getMap().getFromRatio() == 3
+                && proteinProduct == mapping.getTo()
+                && seqDss != map.getFromSeq())
+        {
+          mappedFromLength = MappingUtils.getLength(mapping.getMap()
+                  .getFromRanges());
+          if (mappedFromLength == map.getFromSeq().getLength())
+          {
+            /*
+            * found a 3:1 mapping to the protein product which covers
+            * the whole dna sequence i.e. is from CDS; finally check it
+            * is from the dna start sequence
+            */
+            SequenceI cdsSeq = map.getFromSeq();
+            List<AlignedCodonFrame> dnaToCdsMaps = MappingUtils
+                    .findMappingsForSequence(cdsSeq, seqMappings);
+            if (!dnaToCdsMaps.isEmpty())
+            {
+              return cdsSeq;
+            }
+          }
+        }
       }
     }
-    AlignmentI cds = new Alignment(cdsSeqs.toArray(new SequenceI[cdsSeqs
-            .size()]));
-    cds.setDataset(dataset);
-
-    return cds;
+    return null;
   }
 
   /**
@@ -1477,7 +1842,7 @@ public class AlignmentUtils
    * 
    * @param seq
    * @param mapping
-   * @return
+   * @return CDS sequence (as a dataset sequence)
    */
   static SequenceI makeCdsSequence(SequenceI seq, Mapping mapping)
   {
@@ -1507,9 +1872,15 @@ public class AlignmentUtils
       }
     }
 
-    SequenceI newSeq = new Sequence(seq.getName() + "|"
-            + mapping.getTo().getName(), newSeqChars, 1, newPos);
-    newSeq.createDatasetSequence();
+    /*
+     * assign 'from id' held in the mapping if set (e.g. EMBL protein_id),
+     * else generate a sequence name
+     */
+    String mapFromId = mapping.getMappedFromId();
+    String seqId = "CDS|" + (mapFromId != null ? mapFromId : seq.getName());
+    SequenceI newSeq = new Sequence(seqId, newSeqChars, 1, newPos);
+    // newSeq.setDescription(mapFromId);
+
     return newSeq;
   }
 
@@ -1795,17 +2166,20 @@ public class AlignmentUtils
      * sort to get sequence features in start position order
      * - would be better to store in Sequence as a TreeSet or NCList?
      */
-    Arrays.sort(peptide.getSequenceFeatures(),
-            new Comparator<SequenceFeature>()
-            {
-              @Override
-              public int compare(SequenceFeature o1, SequenceFeature o2)
+    if (peptide.getSequenceFeatures() != null)
+    {
+      Arrays.sort(peptide.getSequenceFeatures(),
+              new Comparator<SequenceFeature>()
               {
-                int c = Integer.compare(o1.getBegin(), o2.getBegin());
-                return c == 0 ? Integer.compare(o1.getEnd(), o2.getEnd())
-                        : c;
-              }
-            });
+                @Override
+                public int compare(SequenceFeature o1, SequenceFeature o2)
+                {
+                  int c = Integer.compare(o1.getBegin(), o2.getBegin());
+                  return c == 0 ? Integer.compare(o1.getEnd(), o2.getEnd())
+                          : c;
+                }
+              });
+    }
     return count;
   }
 
@@ -2107,12 +2481,15 @@ public class AlignmentUtils
    * 
    * @param seqs
    * @param xrefs
+   * @param dataset
+   *          the alignment dataset shared by the new copy
    * @return
    */
   public static AlignmentI makeCopyAlignment(SequenceI[] seqs,
-          SequenceI[] xrefs)
+          SequenceI[] xrefs, AlignmentI dataset)
   {
     AlignmentI copy = new Alignment(new Alignment(seqs));
+    copy.setDataset(dataset);
 
     SequenceIdMatcher matcher = new SequenceIdMatcher(seqs);
     if (xrefs != null)
@@ -2158,6 +2535,17 @@ public class AlignmentUtils
    */
   public static int alignAs(AlignmentI unaligned, AlignmentI aligned)
   {
+    /*
+     * easy case - aligning a copy of aligned sequences
+     */
+    if (alignAsSameSequences(unaligned, aligned))
+    {
+      return unaligned.getHeight();
+    }
+
+    /*
+     * fancy case - aligning via mappings between sequences
+     */
     List<SequenceI> unmapped = new ArrayList<SequenceI>();
     Map<Integer, Map<SequenceI, Character>> columnMap = buildMappedColumnsMap(
             unaligned, aligned, unmapped);
@@ -2210,6 +2598,54 @@ public class AlignmentUtils
   }
 
   /**
+   * If unaligned and aligned sequences share the same dataset sequences, then
+   * simply copies the aligned sequences to the unaligned sequences and returns
+   * true; else returns false
+   * 
+   * @param unaligned
+   * @param aligned
+   * @return
+   */
+  static boolean alignAsSameSequences(AlignmentI unaligned,
+          AlignmentI aligned)
+  {
+    if (aligned.getDataset() == null || unaligned.getDataset() == null)
+    {
+      return false; // should only pass alignments with datasets here
+    }
+
+    Map<SequenceI, SequenceI> alignedDatasets = new HashMap<SequenceI, SequenceI>();
+    for (SequenceI seq : aligned.getSequences())
+    {
+      alignedDatasets.put(seq.getDatasetSequence(), seq);
+    }
+
+    /*
+     * first pass - check whether all sequences to be aligned share a dataset
+     * sequence with an aligned sequence
+     */
+    for (SequenceI seq : unaligned.getSequences())
+    {
+      if (!alignedDatasets.containsKey(seq.getDatasetSequence()))
+      {
+        return false;
+      }
+    }
+
+    /*
+     * second pass - copy aligned sequences
+     */
+    for (SequenceI seq : unaligned.getSequences())
+    {
+      SequenceI alignedSequence = alignedDatasets.get(seq
+              .getDatasetSequence());
+      seq.setSequence(alignedSequence.getSequenceAsString());
+    }
+
+    return true;
+  }
+
+  /**
    * Returns a map whose key is alignment column number (base 1), and whose
    * values are a map of sequence characters in that column.
    * 
@@ -2223,13 +2659,13 @@ public class AlignmentUtils
   {
     /*
      * Map will hold, for each aligned column position, a map of
-     * {unalignedSequence, sequenceCharacter} at that position.
+     * {unalignedSequence, characterPerSequence} at that position.
      * TreeMap keeps the entries in ascending column order. 
      */
     Map<Integer, Map<SequenceI, Character>> map = new TreeMap<Integer, Map<SequenceI, Character>>();
 
     /*
-     * r any sequences that have no mapping so can't be realigned
+     * record any sequences that have no mapping so can't be realigned
      */
     unmapped.addAll(unaligned.getSequences());
 
@@ -2278,6 +2714,15 @@ public class AlignmentUtils
       return false;
     }
 
+    /*
+     * invert mapping if it is from unaligned to aligned sequence
+     */
+    if (seqMap.getTo() == fromSeq.getDatasetSequence())
+    {
+      seqMap = new Mapping(seq.getDatasetSequence(), seqMap.getMap()
+              .getInverse());
+    }
+
     char[] fromChars = fromSeq.getSequence();
     int toStart = seq.getStart();
     char[] toChars = seq.getSequence();
@@ -2311,7 +2756,8 @@ public class AlignmentUtils
          * of the next character of the mapped-to sequence; stop when all
          * the characters of the range have been counted
          */
-        while (mappedCharPos <= range[1])
+        while (mappedCharPos <= range[1] && fromCol <= fromChars.length
+                && fromCol >= 0)
         {
           if (!Comparison.isGap(fromChars[fromCol - 1]))
           {