Computes a vector of numbers of reads falling into successive intervals of specified length (e.g. numbers of reads per every 1Mbase)

git-svn-id: file:///humgen/gsa-scr1/gsa-engineering/svn_contents/trunk@1115 348d0f76-0448-11de-a6fe-93d51630548a

java/src/org/broadinstitute/sting/playground/gatk/walkers/CoarseCoverageWalker.java

@@ -0,0 +1,81 @@
+package org.broadinstitute.sting.playground.gatk.walkers;
+
+import net.sf.samtools.SAMRecord;
+
+import org.broadinstitute.sting.gatk.walkers.ReadWalker;
+import org.broadinstitute.sting.utils.cmdLine.Argument;
+
+public class CoarseCoverageWalker extends ReadWalker<Integer,Integer> {
+	
+    @Argument(fullName="granularity",shortName="G",doc="Will print numbers of reads per every <granularity> bases "+
+    		"on the reference, or on the subset of the reference specified by Intervals (if given). Moving to the next "+
+    		"contig on the reference will always restart the count anew, even if the count of bases in the last chunk on"+
+    		" the previous contig did not reach specified <granularity>.",required=true)
+    public Integer N;
+	
+
+    private int chunkStart = 1; // start of the current chunk we are counting reads for
+    private int contig = 0; // current contig we are on
+    private int count = 0; // number of reads overlapping with the current chunk
+    private static String zeroString = "0";
+    
+    @Override 
+    public void initialize() {
+    	chunkStart = 1;
+    	contig = 0;
+    	count = 0;
+    }
+    
+	@Override
+	public Integer map(char[] ref, SAMRecord read) {
+		
+		if ( read.getReadUnmappedFlag() ||
+			 read.getDuplicateReadFlag() ||
+			 read.getNotPrimaryAlignmentFlag() ||
+			 read.getMappingQuality() == 0 ) return 0;
+		
+		if ( read.getReferenceIndex() != contig ) {
+			// we jumped onto another contig
+			out.printf("%d%n", count); // print old count
+			count = 0;
+			
+			// if we skipped one or more contigs completely, make sure we print 0 counts over all of them:
+			for ( contig++ ; contig < read.getReferenceIndex() ; contig++) {
+				int contigSize = read.getHeader().getSequence(contig).getSequenceLength();
+				for ( int k = 1 ; k < contigSize ;  k+=N ) out.println(zeroString);
+			}
+			// by now we scrolled to the right contig
+			
+			chunkStart = 1; // reset chunk start
+		}
+		
+		// if our read is past the boundary of the current chunk, print old count(s)
+		// (for the current chunk and all chunks we may have skipped altogether) and reinitialize:
+		while ( chunkStart+N < read.getAlignmentStart() ) {
+			out.printf("%d%n", count); // print old count
+			count = 0;
+			chunkStart += N;
+		}
+		count++;
+		return 1;
+	}
+
+	@Override
+	public Integer reduce(Integer value, Integer sum) {
+		return value+sum;
+	}
+
+	@Override
+	public Integer reduceInit() {
+		return 0;
+	}
+	
+	@Override 
+	public void onTraversalDone(Integer result) {
+		out.printf("%d%n", count); // print count from the last chunk
+		super.onTraversalDone(result);
+		
+	}
+	
+
+}