Merge branch 'develop' into feature/JAL-3390hideUnmappedStructure
[jalview.git] / src / jalview / ext / rbvi / chimera / ChimeraCommands.java
index 148f252..45b22f7 100644 (file)
  */
 package jalview.ext.rbvi.chimera;
 
-import java.awt.Color;
-import java.util.ArrayList;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.TreeMap;
-
+import jalview.api.AlignViewportI;
+import jalview.api.AlignmentViewPanel;
 import jalview.api.FeatureRenderer;
 import jalview.api.SequenceRenderer;
 import jalview.datamodel.AlignmentI;
+import jalview.datamodel.HiddenColumns;
+import jalview.datamodel.MappedFeatures;
+import jalview.datamodel.SequenceFeature;
 import jalview.datamodel.SequenceI;
+import jalview.gui.Desktop;
+import jalview.renderer.seqfeatures.FeatureColourFinder;
 import jalview.structure.StructureMapping;
 import jalview.structure.StructureMappingcommandSet;
 import jalview.structure.StructureSelectionManager;
+import jalview.structures.models.AAStructureBindingModel;
 import jalview.util.ColorUtils;
 import jalview.util.Comparison;
+import jalview.util.IntRangeComparator;
+
+import java.awt.Color;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
 
 /**
  * Routines for generating Chimera commands for Jalview/Chimera binding
@@ -45,30 +56,28 @@ import jalview.util.Comparison;
  */
 public class ChimeraCommands
 {
+  public static final String NAMESPACE_PREFIX = "jv_";
+
+  /*
+   * colour for residues shown in structure but hidden in alignment
+   */
+  private static final String COLOR_GRAY_HEX = "color "
+          + ColorUtils.toTkCode(Color.GRAY);
 
   /**
-   * utility to construct the commands to colour chains by the given alignment
-   * for passing to Chimera
-   * 
-   * @returns Object[] { Object[] { <model being coloured>,
+   * Constructs Chimera commands to colour residues as per the Jalview alignment
    * 
+   * @param colourMap
+   * @param binding
+   * @return
    */
-  public static StructureMappingcommandSet[] getColourBySequenceCommand(
-          StructureSelectionManager ssm, String[] files,
-          SequenceI[][] sequence, SequenceRenderer sr, FeatureRenderer fr,
-          AlignmentI alignment)
+  public static String[] getColourBySequenceCommand(
+          Map<Object, AtomSpecModel> colourMap,
+          AAStructureBindingModel binding)
   {
-    Map<Color, Map<Integer, Map<String, List<int[]>>>> colourMap = buildColoursMap(
-            ssm, files, sequence, sr, fr, alignment);
-
-    List<String> colourCommands = buildColourCommands(colourMap);
+    List<String> colourCommands = buildColourCommands(colourMap, binding);
 
-    StructureMappingcommandSet cs = new StructureMappingcommandSet(
-            ChimeraCommands.class, null,
-            colourCommands.toArray(new String[0]));
-
-    return new StructureMappingcommandSet[]
-    { cs };
+    return colourCommands.toArray(new String[colourCommands.size()]);
   }
 
   /**
@@ -76,98 +85,78 @@ public class ChimeraCommands
    * 'color' commands (one per distinct colour used). The format of each command
    * is
    * 
-   * <blockquote> color colorname #modelnumber:range.chain e.g. color #00ff00
-   * #0:2.B,4.B,9-12.B|#1:1.A,2-6.A,...
-   * 
-   * @see http
-   *      ://www.cgl.ucsf.edu/chimera/current/docs/UsersGuide/midas/frameatom_spec
-   *      .html </pre>
+   * <pre>
+   * <blockquote> 
+   * color colorname #modelnumber:range.chain 
+   * e.g. color #00ff00 #0:2.B,4.B,9-12.B|#1:1.A,2-6.A,...
+   * </blockquote>
+   * </pre>
    * 
    * @param colourMap
+   * @param binding
    * @return
    */
   protected static List<String> buildColourCommands(
-          Map<Color, Map<Integer, Map<String, List<int[]>>>> colourMap)
+          Map<Object, AtomSpecModel> colourMap,
+          AAStructureBindingModel binding)
   {
     /*
      * This version concatenates all commands into a single String (semi-colon
      * delimited). If length limit issues arise, refactor to return one color
      * command per colour.
      */
-    List<String> commands = new ArrayList<String>();
+    List<String> commands = new ArrayList<>();
     StringBuilder sb = new StringBuilder(256);
-    boolean firstColour = true;
-    for (Color colour : colourMap.keySet())
+    sb.append(COLOR_GRAY_HEX);
+
+    for (Object key : colourMap.keySet())
     {
+      Color colour = (Color) key;
       String colourCode = ColorUtils.toTkCode(colour);
-      if (!firstColour)
-      {
-        sb.append("; ");
-      }
+      sb.append("; ");
       sb.append("color ").append(colourCode).append(" ");
-      firstColour = false;
-      boolean firstModelForColour = true;
-      final Map<Integer, Map<String, List<int[]>>> colourData = colourMap.get(colour);
-      for (Integer model : colourData.keySet())
-      {
-        boolean firstPositionForModel = true;
-        if (!firstModelForColour)
-        {
-          sb.append("|");
-        }
-        firstModelForColour = false;
-        sb.append("#").append(model).append(":");
-
-        final Map<String, List<int[]>> modelData = colourData.get(model);
-        for (String chain : modelData.keySet())
-        {
-          boolean hasChain = !"".equals(chain.trim());
-          for (int[] range : modelData.get(chain))
-          {
-            if (!firstPositionForModel)
-            {
-              sb.append(",");
-            }
-            if (range[0] == range[1])
-            {
-              sb.append(range[0]);
-            }
-            else
-            {
-              sb.append(range[0]).append("-").append(range[1]);
-            }
-            if (hasChain)
-            {
-              sb.append(".").append(chain);
-            }
-            firstPositionForModel = false;
-          }
-        }
-      }
+      final AtomSpecModel colourData = colourMap.get(colour);
+      sb.append(getAtomSpec(colourData, binding));
     }
     commands.add(sb.toString());
     return commands;
   }
 
   /**
+   * Build a data structure which records contiguous subsequences for each colour.
+   * From this we can easily generate the Chimera command for colour by sequence.
+   * 
    * <pre>
-   * Build a data structure which maps contiguous subsequences for each colour. 
-   * This generates a data structure from which we can easily generate the 
-   * Chimera command for colour by sequence.
    * Color
    *     Model number
    *         Chain
    *             list of start/end ranges
-   * Ordering is by order of addition (for colours and positions), natural ordering (for models and chains)
    * </pre>
+   * 
+   * Ordering is by order of addition (for colours and positions), natural
+   * ordering (for models and chains)
+   * 
+   * @param ssm
+   * @param files
+   * @param sequence
+   * @param sr
+   * @param hideHiddenRegions
+   * @param viewPanel
+   * @return
    */
-  protected static Map<Color, Map<Integer, Map<String, List<int[]>>>> buildColoursMap(
+  protected static Map<Object, AtomSpecModel> buildColoursMap(
           StructureSelectionManager ssm, String[] files,
-          SequenceI[][] sequence, SequenceRenderer sr, FeatureRenderer fr,
-          AlignmentI alignment)
+          SequenceI[][] sequence, SequenceRenderer sr,
+          boolean hideHiddenRegions, AlignmentViewPanel viewPanel)
   {
-    Map<Color, Map<Integer, Map<String, List<int[]>>>> colourMap = new LinkedHashMap<Color, Map<Integer, Map<String, List<int[]>>>>();
+    FeatureRenderer fr = viewPanel.getFeatureRenderer();
+    FeatureColourFinder finder = new FeatureColourFinder(fr);
+    AlignViewportI viewport = viewPanel.getAlignViewport();
+    HiddenColumns cs = viewport.getAlignment().getHiddenColumns();
+    AlignmentI al = viewport.getAlignment();
+    Map<Object, AtomSpecModel> colourMap = new LinkedHashMap<>();
     Color lastColour = null;
+
     for (int pdbfnum = 0; pdbfnum < files.length; pdbfnum++)
     {
       StructureMapping[] mapping = ssm.getMapping(files[pdbfnum]);
@@ -185,9 +174,9 @@ public class ChimeraCommands
         {
           final SequenceI seq = sequence[pdbfnum][s];
           if (mapping[m].getSequence() == seq
-                  && (sp = alignment.findIndex(seq)) > -1)
+                  && (sp = al.findIndex(seq)) > -1)
           {
-            SequenceI asp = alignment.getSequenceAt(sp);
+            SequenceI asp = al.getSequenceAt(sp);
             for (int r = 0; r < asp.getLength(); r++)
             {
               // no mapping to gaps in sequence
@@ -202,7 +191,23 @@ public class ChimeraCommands
                 continue;
               }
 
-              Color colour = sr.getResidueColour(seq, r, fr);
+              Color colour = sr.getResidueColour(seq, r, finder);
+
+              /*
+               * hidden regions are shown gray or, optionally, ignored
+               */
+              if (!cs.isVisible(r))
+              {
+                if (hideHiddenRegions)
+                {
+                  continue;
+                }
+                else
+                {
+                  colour = Color.GRAY;
+                }
+              }
+
               final String chain = mapping[m].getChain();
 
               /*
@@ -217,7 +222,7 @@ public class ChimeraCommands
               {
                 if (startPos != -1)
                 {
-                  addColourRange(colourMap, lastColour, pdbfnum, startPos,
+                  addAtomSpecRange(colourMap, lastColour, pdbfnum, startPos,
                           lastPos, lastChain);
                 }
                 startPos = pos;
@@ -229,10 +234,10 @@ public class ChimeraCommands
             // final colour range
             if (lastColour != null)
             {
-              addColourRange(colourMap, lastColour, pdbfnum, startPos,
+              addAtomSpecRange(colourMap, lastColour, pdbfnum, startPos,
                       lastPos, lastChain);
             }
-            break;
+            // break;
           }
         }
       }
@@ -241,54 +246,486 @@ public class ChimeraCommands
   }
 
   /**
-   * Helper method to add one contiguous colour range to the colour map.
+   * Helper method to add one contiguous range to the AtomSpec model for the given
+   * value (creating the model if necessary). As used by Jalview, {@code value} is
+   * <ul>
+   * <li>a colour, when building a 'colour structure by sequence' command</li>
+   * <li>a feature value, when building a 'set Chimera attributes from features'
+   * command</li>
+   * </ul>
    * 
-   * @param colourMap
-   * @param colour
+   * @param map
+   * @param value
    * @param model
    * @param startPos
    * @param endPos
    * @param chain
    */
-  protected static void addColourRange(
-          Map<Color, Map<Integer, Map<String, List<int[]>>>> colourMap,
-          Color colour, int model, int startPos, int endPos, String chain)
+  public static void addAtomSpecRange(Map<Object, AtomSpecModel> map,
+          Object value, int model, int startPos, int endPos, String chain)
   {
     /*
      * Get/initialize map of data for the colour
      */
-    Map<Integer, Map<String, List<int[]>>> colourData = colourMap
-            .get(colour);
-    if (colourData == null)
+    AtomSpecModel atomSpec = map.get(value);
+    if (atomSpec == null)
+    {
+      atomSpec = new AtomSpecModel();
+      map.put(value, atomSpec);
+    }
+
+    atomSpec.addRange(model, startPos, endPos, chain);
+  }
+
+  /**
+   * Constructs and returns Chimera commands to set attributes on residues
+   * corresponding to features in Jalview. Attribute names are the Jalview feature
+   * type, with a "jv_" prefix.
+   * 
+   * @param ssm
+   * @param files
+   * @param seqs
+   * @param viewPanel
+   * @param binding
+   * @return
+   */
+  public static StructureMappingcommandSet getSetAttributeCommandsForFeatures(
+          AlignmentViewPanel viewPanel, AAStructureBindingModel binding)
+  {
+    StructureSelectionManager ssm = binding.getSsm();
+    String[] files = binding.getStructureFiles();
+    SequenceI[][] seqs = binding.getSequence();
+
+    Map<String, Map<Object, AtomSpecModel>> featureMap = buildFeaturesMap(
+            ssm, files, seqs, viewPanel);
+
+    List<String> commands = buildSetAttributeCommands(featureMap, binding);
+
+    StructureMappingcommandSet cs = new StructureMappingcommandSet(
+            ChimeraCommands.class, null,
+            commands.toArray(new String[commands.size()]));
+
+    return cs;
+  }
+
+  /**
+   * <pre>
+   * Helper method to build a map of 
+   *   { featureType, { feature value, AtomSpecModel } }
+   * </pre>
+   * 
+   * @param ssm
+   * @param files
+   * @param seqs
+   * @param viewPanel
+   * @return
+   */
+  protected static Map<String, Map<Object, AtomSpecModel>> buildFeaturesMap(
+          StructureSelectionManager ssm, String[] files, SequenceI[][] seqs,
+          AlignmentViewPanel viewPanel)
+  {
+    Map<String, Map<Object, AtomSpecModel>> theMap = new LinkedHashMap<>();
+
+    FeatureRenderer fr = viewPanel.getFeatureRenderer();
+    if (fr == null)
     {
-      colourMap
-              .put(colour,
-                      colourData = new TreeMap<Integer, Map<String, List<int[]>>>());
+      return theMap;
     }
 
+    AlignViewportI viewport = viewPanel.getAlignViewport();
+    List<String> visibleFeatures = fr.getDisplayedFeatureTypes();
+
     /*
-     * Get/initialize map of data for the colour and model
+     * if alignment is showing features from complement, we also transfer
+     * these features to the corresponding mapped structure residues
      */
-    Map<String, List<int[]>> modelData = colourData.get(model);
-    if (modelData == null)
+    boolean showLinkedFeatures = viewport.isShowComplementFeatures();
+    List<String> complementFeatures = new ArrayList<>();
+    FeatureRenderer complementRenderer = null;
+    if (showLinkedFeatures)
+    {
+      AlignViewportI comp = fr.getViewport().getCodingComplement();
+      if (comp != null)
+      {
+        complementRenderer = Desktop.getAlignFrameFor(comp)
+                .getFeatureRenderer();
+        complementFeatures = complementRenderer.getDisplayedFeatureTypes();
+      }
+    }
+    if (visibleFeatures.isEmpty() && complementFeatures.isEmpty())
+    {
+      return theMap;
+    }
+
+    AlignmentI alignment = viewPanel.getAlignment();
+    for (int pdbfnum = 0; pdbfnum < files.length; pdbfnum++)
     {
-      colourData.put(model, modelData = new TreeMap<String, List<int[]>>());
+      StructureMapping[] mapping = ssm.getMapping(files[pdbfnum]);
+
+      if (mapping == null || mapping.length < 1)
+      {
+        continue;
+      }
+
+      for (int seqNo = 0; seqNo < seqs[pdbfnum].length; seqNo++)
+      {
+        for (int m = 0; m < mapping.length; m++)
+        {
+          final SequenceI seq = seqs[pdbfnum][seqNo];
+          int sp = alignment.findIndex(seq);
+          StructureMapping structureMapping = mapping[m];
+          if (structureMapping.getSequence() == seq && sp > -1)
+          {
+            /*
+             * found a sequence with a mapping to a structure;
+             * now scan its features
+             */
+            if (!visibleFeatures.isEmpty())
+            {
+              scanSequenceFeatures(visibleFeatures, structureMapping, seq,
+                      theMap, pdbfnum);
+            }
+            if (showLinkedFeatures)
+            {
+              scanComplementFeatures(complementRenderer, structureMapping,
+                      seq, theMap, pdbfnum);
+            }
+          }
+        }
+      }
     }
+    return theMap;
+  }
 
+  /**
+   * Scans visible features in mapped positions of the CDS/peptide complement, and
+   * adds any found to the map of attribute values/structure positions
+   * 
+   * @param complementRenderer
+   * @param structureMapping
+   * @param seq
+   * @param theMap
+   * @param modelNumber
+   */
+  protected static void scanComplementFeatures(
+          FeatureRenderer complementRenderer,
+          StructureMapping structureMapping, SequenceI seq,
+          Map<String, Map<Object, AtomSpecModel>> theMap, int modelNumber)
+  {
     /*
-     * Get/initialize map of data for colour, model and chain
+     * for each sequence residue mapped to a structure position...
      */
-    List<int[]> chainData = modelData.get(chain);
-    if (chainData == null)
+    for (int seqPos : structureMapping.getMapping().keySet())
+    {
+      /*
+       * find visible complementary features at mapped position(s)
+       */
+      MappedFeatures mf = complementRenderer
+              .findComplementFeaturesAtResidue(seq, seqPos);
+      if (mf != null)
+      {
+        for (SequenceFeature sf : mf.features)
+        {
+          String type = sf.getType();
+
+          /*
+           * Don't copy features which originated from Chimera
+           */
+          if (JalviewChimeraBinding.CHIMERA_FEATURE_GROUP
+                  .equals(sf.getFeatureGroup()))
+          {
+            continue;
+          }
+
+          /*
+           * record feature 'value' (score/description/type) as at the
+           * corresponding structure position
+           */
+          List<int[]> mappedRanges = structureMapping
+                  .getPDBResNumRanges(seqPos, seqPos);
+
+          if (!mappedRanges.isEmpty())
+          {
+            String value = sf.getDescription();
+            if (value == null || value.length() == 0)
+            {
+              value = type;
+            }
+            float score = sf.getScore();
+            if (score != 0f && !Float.isNaN(score))
+            {
+              value = Float.toString(score);
+            }
+            Map<Object, AtomSpecModel> featureValues = theMap.get(type);
+            if (featureValues == null)
+            {
+              featureValues = new HashMap<>();
+              theMap.put(type, featureValues);
+            }
+            for (int[] range : mappedRanges)
+            {
+              addAtomSpecRange(featureValues, value, modelNumber, range[0],
+                      range[1], structureMapping.getChain());
+            }
+          }
+        }
+      }
+    }
+  }
+
+  /**
+   * Inspect features on the sequence; for each feature that is visible, determine
+   * its mapped ranges in the structure (if any) according to the given mapping,
+   * and add them to the map.
+   * 
+   * @param visibleFeatures
+   * @param mapping
+   * @param seq
+   * @param theMap
+   * @param modelNumber
+   */
+  protected static void scanSequenceFeatures(List<String> visibleFeatures,
+          StructureMapping mapping, SequenceI seq,
+          Map<String, Map<Object, AtomSpecModel>> theMap, int modelNumber)
+  {
+    List<SequenceFeature> sfs = seq.getFeatures().getPositionalFeatures(
+            visibleFeatures.toArray(new String[visibleFeatures.size()]));
+    for (SequenceFeature sf : sfs)
+    {
+      String type = sf.getType();
+
+      /*
+       * Don't copy features which originated from Chimera
+       */
+      if (JalviewChimeraBinding.CHIMERA_FEATURE_GROUP
+              .equals(sf.getFeatureGroup()))
+      {
+        continue;
+      }
+
+      List<int[]> mappedRanges = mapping.getPDBResNumRanges(sf.getBegin(),
+              sf.getEnd());
+
+      if (!mappedRanges.isEmpty())
+      {
+        String value = sf.getDescription();
+        if (value == null || value.length() == 0)
+        {
+          value = type;
+        }
+        float score = sf.getScore();
+        if (score != 0f && !Float.isNaN(score))
+        {
+          value = Float.toString(score);
+        }
+        Map<Object, AtomSpecModel> featureValues = theMap.get(type);
+        if (featureValues == null)
+        {
+          featureValues = new HashMap<>();
+          theMap.put(type, featureValues);
+        }
+        for (int[] range : mappedRanges)
+        {
+          addAtomSpecRange(featureValues, value, modelNumber, range[0],
+                  range[1], mapping.getChain());
+        }
+      }
+    }
+  }
+
+  /**
+   * Traverse the map of features/values/models/chains/positions to construct a
+   * list of 'setattr' commands (one per distinct feature type and value).
+   * <p>
+   * The format of each command is
+   * 
+   * <pre>
+   * <blockquote> setattr r <featureName> " " #modelnumber:range.chain 
+   * e.g. setattr r jv:chain <value> #0:2.B,4.B,9-12.B|#1:1.A,2-6.A,...
+   * </blockquote>
+   * </pre>
+   * 
+   * @param featureMap
+   * @param binding
+   * @return
+   */
+  protected static List<String> buildSetAttributeCommands(
+          Map<String, Map<Object, AtomSpecModel>> featureMap,
+          AAStructureBindingModel binding)
+  {
+    List<String> commands = new ArrayList<>();
+    for (String featureType : featureMap.keySet())
+    {
+      String attributeName = makeAttributeName(featureType);
+
+      /*
+       * clear down existing attributes for this feature
+       */
+      // 'problem' - sets attribute to None on all residues - overkill?
+      // commands.add("~setattr r " + attributeName + " :*");
+
+      Map<Object, AtomSpecModel> values = featureMap.get(featureType);
+      for (Object value : values.keySet())
+      {
+        /*
+         * for each distinct value recorded for this feature type,
+         * add a command to set the attribute on the mapped residues
+         * Put values in single quotes, encoding any embedded single quotes
+         */
+        StringBuilder sb = new StringBuilder(128);
+        String featureValue = value.toString();
+        featureValue = featureValue.replaceAll("\\'", "&#39;");
+        sb.append("setattr r ").append(attributeName).append(" '")
+                .append(featureValue).append("' ");
+        sb.append(getAtomSpec(values.get(value), binding));
+        commands.add(sb.toString());
+      }
+    }
+
+    return commands;
+  }
+
+  /**
+   * Makes a prefixed and valid Chimera attribute name. A jv_ prefix is applied
+   * for a 'Jalview' namespace, and any non-alphanumeric character is converted
+   * to an underscore.
+   * 
+   * @param featureType
+   * @return
+   * 
+   *         <pre>
+   * &#64;see https://www.cgl.ucsf.edu/chimera/current/docs/UsersGuide/midas/setattr.html
+   *         </pre>
+   */
+  protected static String makeAttributeName(String featureType)
+  {
+    StringBuilder sb = new StringBuilder();
+    if (featureType != null)
     {
-      modelData.put(chain, chainData = new ArrayList<int[]>());
+      for (char c : featureType.toCharArray())
+      {
+        sb.append(Character.isLetterOrDigit(c) ? c : '_');
+      }
     }
+    String attName = NAMESPACE_PREFIX + sb.toString();
 
     /*
-     * Add the start/end positions
+     * Chimera treats an attribute name ending in 'color' as colour-valued;
+     * Jalview doesn't, so prevent this by appending an underscore
      */
-    chainData.add(new int[]
-    { startPos, endPos });
+    if (attName.toUpperCase().endsWith("COLOR"))
+    {
+      attName += "_";
+    }
+
+    return attName;
+  }
+
+  /**
+   * Returns the range(s) formatted as a Chimera atomspec
+   * 
+   * @return
+   */
+  public static String getAtomSpec(AtomSpecModel atomSpec,
+          AAStructureBindingModel binding)
+  {
+    StringBuilder sb = new StringBuilder(128);
+    boolean firstModel = true;
+    for (Integer model : atomSpec.getModels())
+    {
+      if (!firstModel)
+      {
+        sb.append("|");
+      }
+      firstModel = false;
+      // todo use JalviewChimeraBinding.getModelSpec(model)
+      // which means this cannot be static
+      sb.append(binding.getModelSpec(model)).append(":");
+
+      boolean firstPositionForModel = true;
+
+      for (String chain : atomSpec.getChains(model))
+      {
+        chain = " ".equals(chain) ? chain : chain.trim();
+
+        List<int[]> rangeList = atomSpec.getRanges(model, chain);
+
+        /*
+         * sort ranges into ascending start position order
+         */
+        Collections.sort(rangeList, IntRangeComparator.ASCENDING);
+
+        int start = rangeList.isEmpty() ? 0 : rangeList.get(0)[0];
+        int end = rangeList.isEmpty() ? 0 : rangeList.get(0)[1];
+
+        Iterator<int[]> iterator = rangeList.iterator();
+        while (iterator.hasNext())
+        {
+          int[] range = iterator.next();
+          if (range[0] <= end + 1)
+          {
+            /*
+             * range overlaps or is contiguous with the last one
+             * - so just extend the end position, and carry on
+             * (unless this is the last in the list)
+             */
+            end = Math.max(end, range[1]);
+          }
+          else
+          {
+            /*
+             * we have a break so append the last range
+             */
+            appendRange(sb, start, end, chain, firstPositionForModel);
+            firstPositionForModel = false;
+            start = range[0];
+            end = range[1];
+          }
+        }
+
+        /*
+         * and append the last range
+         */
+        if (!rangeList.isEmpty())
+        {
+          appendRange(sb, start, end, chain, firstPositionForModel);
+          firstPositionForModel = false;
+        }
+      }
+    }
+    return sb.toString();
+  }
+
+  /**
+   * A helper method that appends one start-end range to a Chimera atomspec
+   * 
+   * @param sb
+   * @param start
+   * @param end
+   * @param chain
+   * @param firstPositionForModel
+   */
+  static void appendRange(StringBuilder sb, int start, int end,
+          String chain, boolean firstPositionForModel)
+  {
+    if (!firstPositionForModel)
+    {
+      sb.append(",");
+    }
+    if (end == start)
+    {
+      sb.append(start);
+    }
+    else
+    {
+      sb.append(start).append("-").append(end);
+    }
+
+    sb.append(".");
+    if (!" ".equals(chain))
+    {
+      sb.append(chain);
+    }
   }
 
 }