diff --git a/java/src/org/broadinstitute/sting/playground/gatk/walkers/diagnostics/SNPDensity.java b/java/src/org/broadinstitute/sting/playground/gatk/walkers/diagnostics/SNPDensity.java
new file mode 100755
index 000000000..f300ae29f
--- /dev/null
+++ b/java/src/org/broadinstitute/sting/playground/gatk/walkers/diagnostics/SNPDensity.java
@@ -0,0 +1,114 @@
+package org.broadinstitute.sting.playground.gatk.walkers.diagnostics;
+
+import org.broadinstitute.sting.gatk.walkers.*;
+import org.broadinstitute.sting.gatk.refdata.RefMetaDataTracker;
+import org.broadinstitute.sting.gatk.refdata.ReferenceOrderedDatum;
+import org.broadinstitute.sting.gatk.refdata.RODRecordList;
+import org.broadinstitute.sting.gatk.refdata.RodVCF;
+import org.broadinstitute.sting.gatk.contexts.ReferenceContext;
+import org.broadinstitute.sting.gatk.contexts.AlignmentContext;
+import org.broadinstitute.sting.utils.cmdLine.Argument;
+import org.broadinstitute.sting.utils.StingException;
+import org.broadinstitute.sting.utils.PackageUtils;
+import org.broadinstitute.sting.utils.GenomeLoc;
+import org.broadinstitute.sting.utils.Pair;
+import org.broadinstitute.sting.utils.genotype.Genotype;
+import org.broadinstitute.sting.utils.genotype.Variation;
+import org.broadinstitute.sting.utils.genotype.vcf.VCFRecord;
+import org.broadinstitute.sting.utils.genotype.vcf.VCFGenotypeEncoding;
+import org.broadinstitute.sting.utils.genotype.vcf.VCFGenotypeRecord;
+import org.broadinstitute.sting.playground.gatk.walkers.varianteval.VariantAnalysis;
+import org.broadinstitute.sting.playground.gatk.walkers.diagnostics.newvarianteval.VariantEvaluation;
+import org.broadinstitute.sting.oneoffprojects.variantcontext.VariantContext;
+import org.broadinstitute.sting.oneoffprojects.variantcontext.VariantContextAdaptors;
+import org.apache.commons.jexl.ExpressionFactory;
+import org.apache.commons.jexl.Expression;
+import org.apache.commons.jexl.JexlHelper;
+import org.apache.commons.jexl.JexlContext;
+
+import java.util.*;
+
+/**
+ * Computes the density of SNPs passing and failing filters in intervals on the genome and emits a table for display
+ */
+@By(DataSource.REFERENCE)
+@Requires(value={},referenceMetaData=@RMD(name="eval",type=RodVCF.class))
+public class SNPDensity extends RefWalker<Pair<VariantContext, GenomeLoc>, SNPDensity.Counter> {
+    @Argument(fullName="granularity", shortName="granularity", doc="", required=false)
+    private int granularity = 1000000;
+
+    public void initialize() {
+        out.printf("chr middlePos   linearPos   nSNPs   nSNPsFiltered   unfiltered.density filtered.density%n");
+    }
+
+    public class Counter {
+        GenomeLoc firstLoc = null;
+        long linearOffset = 0;
+        int nSNPsCalled = 0;
+        int nSNPsFiltered = 0;
+
+        public Counter(Long linearOffset) {
+            this.linearOffset = linearOffset;
+            //System.out.printf("linear offset %d%n", linearOffset);
+        }
+    }
+
+    public Pair<VariantContext, GenomeLoc> map(RefMetaDataTracker tracker, ReferenceContext ref, AlignmentContext context) {
+        VariantContext vc = null;
+
+        RODRecordList<ReferenceOrderedDatum> vcfList = tracker.getTrackData("eval", null);
+        if (vcfList != null) {
+            for (ReferenceOrderedDatum d : vcfList) {
+                RodVCF vcfRecord = (RodVCF)d;
+                vc = VariantContextAdaptors.vcfToVariantContext(vcfRecord);
+                break;
+            }
+        }
+
+        return new Pair<VariantContext, GenomeLoc>(vc, context.getLocation());
+    }
+
+    public Counter reduceInit() {
+        return new Counter(0L);
+    }
+
+    private void printLine(Counter sum) {
+        long offset = granularity / 2 - 1;
+        long chrOffset = sum.firstLoc.getStart() + offset;
+        out.printf("%s  %d  %d    %d    %d  %.2e    %.2e%n",
+                sum.firstLoc.getContig(),
+                chrOffset,
+                sum.linearOffset + offset,
+                sum.nSNPsCalled, sum.nSNPsFiltered,
+                (1.0 * sum.nSNPsCalled) / granularity, (1.0 * sum.nSNPsFiltered) / granularity);
+    }
+
+    public Counter reduce(Pair<VariantContext, GenomeLoc> p, Counter sum) {
+        if ( p == null )
+            return sum;
+
+//        System.out.printf("%s %s %d%n", c.getLocation(), sum.firstLoc, sum.nSNPsSeen);
+        VariantContext c = p.getFirst();
+        GenomeLoc loc = p.getSecond();
+
+        if ( sum.firstLoc != null ) {
+            long dist = loc.distance(sum.firstLoc);
+//            System.out.printf("  dist = %d%n", dist);
+            if ( dist > granularity ) {
+                printLine(sum);
+                sum = new Counter(sum.linearOffset + granularity);
+            }
+        }
+
+        if ( sum.firstLoc == null ) sum.firstLoc = loc;
+
+        sum.nSNPsCalled         += c != null && c.isNotFiltered() ? 1 : 0;
+        sum.nSNPsFiltered += c != null && c.isFiltered() ? 1 : 0;
+
+        return sum;
+    }
+
+    public void onTraversalDone(Counter sum) {
+        printLine(sum);
+    }
+}
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