JAL-4019 improvement to short sequence nucleotide detection, and some tidying of...
[jalview.git] / src / jalview / util / Comparison.java
index 2dcbeb5..af6052c 100644 (file)
@@ -23,6 +23,8 @@ package jalview.util;
 import java.util.ArrayList;
 import java.util.List;
 
+import jalview.bin.Cache;
+import jalview.bin.Console;
 import jalview.datamodel.SequenceI;
 
 /**
@@ -32,9 +34,13 @@ public class Comparison
 {
   private static final int EIGHTY_FIVE = 85;
 
-  private static final int NINETY_NINE = 99;
+  private static final int NUCLEOTIDE_COUNT_PERCENT;
 
-  private static final int TO_UPPER_CASE = 'a' - 'A';
+  private static final int NUCLEOTIDE_COUNT_LONG_SEQUENCE_AMBIGUITY_PERCENT;
+
+  private static final int NUCLEOTIDE_COUNT_SHORT_SEQUENCE;
+
+  private static final int NUCLEOTIDE_COUNT_VERY_SHORT_SEQUENCE;
 
   public static final char GAP_SPACE = ' ';
 
@@ -46,6 +52,18 @@ public class Comparison
           new char[]
           { GAP_SPACE, GAP_DOT, GAP_DASH });
 
+  static
+  {
+    NUCLEOTIDE_COUNT_PERCENT = Cache.getDefault("NUCLEOTIDE_COUNT_PERCENT",
+            55);
+    NUCLEOTIDE_COUNT_LONG_SEQUENCE_AMBIGUITY_PERCENT = Cache.getDefault(
+            "NUCLEOTIDE_COUNT_LONG_SEQUENCE_AMBIGUITY_PERCENT", 95);
+    NUCLEOTIDE_COUNT_SHORT_SEQUENCE = Cache
+            .getDefault("NUCLEOTIDE_COUNT_SHORT", 100);
+    NUCLEOTIDE_COUNT_VERY_SHORT_SEQUENCE = Cache
+            .getDefault("NUCLEOTIDE_COUNT_VERY_SHORT", 4);
+  }
+
   /**
    * DOCUMENT ME!
    * 
@@ -93,7 +111,6 @@ public class Comparison
       jlen--;
     }
 
-    int count = 0;
     int match = 0;
     float pid = -1;
 
@@ -106,8 +123,6 @@ public class Comparison
         {
           match++;
         }
-
-        count++;
       }
 
       pid = (float) match / (float) ilen * 100;
@@ -121,8 +136,6 @@ public class Comparison
         {
           match++;
         }
-
-        count++;
       }
 
       pid = (float) match / (float) jlen * 100;
@@ -270,14 +283,16 @@ public class Comparison
    */
   public static final boolean isNucleotide(SequenceI seq)
   {
-    if (seq == null)
+    if (seq == null || seq.getLength() == 0)
     {
       return false;
     }
-    long ntCount = 0;
-    long aaCount = 0;
-    long nCount = 0;
-    long ntaCount = 0;
+    long ntCount = 0; // nucleotide symbol count (does not include ntaCount)
+    long aaCount = 0; // non-nucleotide, non-gap symbol count (includes nCount
+                      // and ntaCount)
+    long nCount = 0; // "Unknown" (N) symbol count
+    long xCount = 0; // Also used as "Unknown" (X) symbol count
+    long ntaCount = 0; // nucleotide ambiguity symbol count
 
     int len = seq.getLength();
     for (int i = 0; i < len; i++)
@@ -296,6 +311,10 @@ public class Comparison
         }
         else
         {
+          if (isX(c))
+          {
+            xCount++;
+          }
           if (isNucleotideAmbiguity(c))
           {
             ntaCount++;
@@ -303,25 +322,98 @@ public class Comparison
         }
       }
     }
-    /*
-     * Check for nucleotide count > 85% of total count (in a form that evades
-     * int / float conversion or divide by zero).
-     */
-    if ((ntCount + nCount) * 100 > EIGHTY_FIVE * (ntCount + aaCount))
+    long allCount = ntCount + aaCount;
+
+    if (Cache.getDefault("NUCLEOTIDE_AMBIGUITY_DETECTION", true))
     {
-      return ntCount > 0; // all N is considered protein. Could use a threshold
-                          // here too
+      Console.info("Performing new nucleotide detection routine");
+      if (allCount > NUCLEOTIDE_COUNT_SHORT_SEQUENCE)
+      {
+        // a long sequence.
+        // check for at least 55% nucleotide, and nucleotide and ambiguity codes
+        // (including N) must make up 95%
+        return ntCount * 100 > NUCLEOTIDE_COUNT_PERCENT * allCount
+                && 100 * (ntCount + nCount
+                        + ntaCount) > NUCLEOTIDE_COUNT_LONG_SEQUENCE_AMBIGUITY_PERCENT
+                                * allCount;
+      }
+      else if (allCount > NUCLEOTIDE_COUNT_VERY_SHORT_SEQUENCE)
+      {
+        // a short sequence.
+        // check if a short sequence is at least 55% nucleotide and the rest of
+        // the symbols are all X or all N
+        if (ntCount * 100 > NUCLEOTIDE_COUNT_PERCENT * allCount
+                && (nCount == aaCount || xCount == aaCount))
+        {
+          return true;
+        }
+
+        // a short sequence.
+        // check for at least x% nucleotide and all the rest nucleotide
+        // ambiguity codes (including N), where x slides from 75% for sequences
+        // of length 4 (i.e. only one non-nucleotide) to 55% for sequences of
+        // length 100
+        return myShortSequenceNucleotideProportionCount(ntCount, allCount)
+                && nCount + ntaCount == aaCount;
+      }
+      else
+      {
+        // a very short sequence. (<4)
+        // all bases must be nucleotide
+        return ntCount > 0 && ntCount == allCount;
+      }
     }
     else
     {
-      // check for very large proportion of nucleotide and all ambiguity codes
-      if ((ntCount + nCount + ntaCount) * 100 >= NINETY_NINE
-              * (ntCount + aaCount))
+      Console.info("Performing old nucleotide detection routine");
+      /*
+       * Check for nucleotide count > 85% of total count (in a form that evades
+       * int / float conversion or divide by zero).
+       */
+      if ((ntCount + nCount) * 100 > EIGHTY_FIVE * allCount)
       {
-        return ntCount > 0;
+        return ntCount > 0; // all N is considered protein. Could use a
+                            // threshold here too
       }
-      return false;
     }
+    return false;
+  }
+
+  protected static boolean myShortSequenceNucleotideProportionCount(
+          long ntCount, long allCount)
+  {
+    /**
+     * this method is valid only for NUCLEOTIDE_COUNT_VERY_SHORT_SEQUENCE <=
+     * allCount <= NUCLEOTIDE_COUNT_SHORT_SEQUENCE
+     */
+    // the following is a simplified integer version of:
+    //
+    // a := allCount # the number of bases in the sequence
+    // n : = ntCount # the number of definite nucleotide bases
+    // vs := NUCLEOTIDE_COUNT_VERY_SHORT_SEQUENCE
+    // s := NUCLEOTIDE_COUNT_SHORT_SEQUENCE
+    // lp := NUCLEOTIDE_COUNT_LOWER_PERCENT
+    // vsp := 1 - (1/a) # this is the proportion of required nucleotides in
+    // # a VERY_SHORT Sequence (4 bases).
+    // # should be all but one base is nucleotide.
+    // p := (a - vs)/(s - vs) # proportion of the way between
+    // # VERY_SHORT and SHORT thresholds.
+    // tp := vsp + p * (lp/100 - vsp) # the proportion of nucleotides
+    // # required for this length of sequence.
+    // minNt := tp * a # the minimum number of definite nucleotide bases
+    // # required for this length of sequences.
+    //
+    // We are then essentially returning:
+    // # ntCount >= 55% of allCount and the rest are all nucleotide ambiguity
+    // ntCount >= tp * allCount && nCount + ntaCount == aaCount
+    // but without going into float/double land
+    long LHS = 100 * allCount
+            * (NUCLEOTIDE_COUNT_SHORT_SEQUENCE
+                    - NUCLEOTIDE_COUNT_VERY_SHORT_SEQUENCE)
+            * (ntCount - allCount + 1);
+    long RHS = allCount * (allCount - NUCLEOTIDE_COUNT_VERY_SHORT_SEQUENCE)
+            * (allCount * NUCLEOTIDE_COUNT_PERCENT - 100 * allCount + 100);
+    return LHS >= RHS;
   }
 
   /**
@@ -369,7 +461,10 @@ public class Comparison
     return isNucleotide(c, false);
   }
 
-  public static boolean isNucleotide(char c, boolean countAmbiguity)
+  /**
+   * includeAmbiguity = true also includes Nucleotide Ambiguity codes
+   */
+  public static boolean isNucleotide(char c, boolean includeAmbiguity)
   {
     char C = Character.toUpperCase(c);
     switch (C)
@@ -381,7 +476,7 @@ public class Comparison
     case 'U':
       return true;
     }
-    if (countAmbiguity)
+    if (includeAmbiguity)
     {
       boolean ambiguity = isNucleotideAmbiguity(C);
       if (ambiguity)
@@ -390,6 +485,9 @@ public class Comparison
     return false;
   }
 
+  /**
+   * Tests *only* nucleotide ambiguity codes (and not definite nucleotide codes)
+   */
   public static boolean isNucleotideAmbiguity(char c)
   {
     switch (Character.toUpperCase(c))
@@ -432,6 +530,12 @@ public class Comparison
    */
   public static boolean isNucleotideSequence(String s, boolean allowGaps)
   {
+    return isNucleotideSequence(s, allowGaps, false);
+  }
+
+  public static boolean isNucleotideSequence(String s, boolean allowGaps,
+          boolean includeAmbiguous)
+  {
     if (s == null)
     {
       return false;
@@ -439,7 +543,7 @@ public class Comparison
     for (int i = 0; i < s.length(); i++)
     {
       char c = s.charAt(i);
-      if (!isNucleotide(c))
+      if (!isNucleotide(c, includeAmbiguous))
       {
         if (!allowGaps || !isGap(c))
         {