gatk-3.8/java/src/org/broadinstitute/sting/alignment/AlignmentValidationWalker.java

package org.broadinstitute.sting.alignment;

import org.broadinstitute.sting.gatk.walkers.ReadWalker;
import org.broadinstitute.sting.utils.BaseUtils;
import org.broadinstitute.sting.utils.StingException;
import org.broadinstitute.sting.utils.cmdLine.Argument;
import org.broadinstitute.sting.alignment.bwa.c.BWACAligner;
import org.broadinstitute.sting.alignment.bwa.c.BWACConfiguration;
import net.sf.samtools.SAMRecord;

import java.util.Iterator;

/**
 * Validates alignments against existing reads.
 *
 * @author mhanna
 * @version 0.1
 */
public class AlignmentValidationWalker extends ReadWalker<Integer,Integer> {
    /**
     * The supporting BWT index generated using BWT. 
     */
    @Argument(fullName="BWTPrefix",shortName="BWT",doc="Index files generated by bwa index -d bwtsw",required=false)
    String prefix = "/Users/mhanna/reference/Ecoli/Escherichia_coli_K12_MG1655.fasta";

    /**
     * The instance used to generate alignments.
     */
    private BWACAligner aligner = null;

    /**
     * Number of reads processed.
     */
    private int count = 0;

    /**
     * Create an aligner object.  The aligner object will load and hold the BWT until close() is called.
     */
    @Override
    public void initialize() {
        BWACConfiguration configuration = new BWACConfiguration(prefix);
        aligner = new BWACAligner(configuration);
    }

    /** Must return true for reads that need to be processed. Reads, for which this method return false will
     * be skipped by the engine and never passed to the walker.
     */
    @Override
    public boolean filter(char[] ref, SAMRecord read) {
        return true;
        //return read.getReadName().contains("SL-XBC:1:61:1719:1512#0");
    }

    /**
     * Aligns a read to the given reference.
     * @param ref Reference over the read.  Read will most likely be unmapped, so ref will be null.
     * @param read Read to align.
     * @return Number of reads aligned by this map (aka 1).
     */
    @Override
    public Integer map(char[] ref, SAMRecord read) {
        //logger.info(String.format("examining read %s", read.getReadName()));

        byte[] bases = read.getReadBases();
        if(read.getReadNegativeStrandFlag()) bases = BaseUtils.simpleReverseComplement(bases);

        boolean matches = true;
        Iterator<Alignment[]> alignments = aligner.getAlignments(bases);

        if(!alignments.hasNext()) {
            matches = read.getReadUnmappedFlag();
        }
        else {
            Alignment[] alignmentsOfBestQuality = alignments.next();
            for(Alignment alignment: alignmentsOfBestQuality) {
                matches = (alignment.getContigIndex() == read.getReferenceIndex());
                matches &= (alignment.getAlignmentStart() == read.getAlignmentStart());
                matches &= (alignment.isNegativeStrand() == read.getReadNegativeStrandFlag());
                matches &= (alignment.getCigar().equals(read.getCigar()));
                matches &= (alignment.getMappingQuality() == read.getMappingQuality());
                if(matches) break;
            }
        }

        if(!matches) {
            logger.error("Found mismatch!");
            logger.error(String.format("Read %s:",read.getReadName()));
            logger.error(String.format("    Contig index: %d",read.getReferenceIndex()));
            logger.error(String.format("    Alignment start: %d", read.getAlignmentStart()));
            logger.error(String.format("    Negative strand: %b", read.getReadNegativeStrandFlag()));
            logger.error(String.format("    Cigar: %s%n", read.getCigarString()));
            logger.error(String.format("    Mapping quality: %s%n", read.getMappingQuality()));
            Alignment[] allAlignments = aligner.getAllAlignments(bases);
            for(int i = 0; i < allAlignments.length; i++) {
                logger.error(String.format("Alignment %d:",i));
                logger.error(String.format("    Contig index: %d",allAlignments[i].getContigIndex()));
                logger.error(String.format("    Alignment start: %d", allAlignments[i].getAlignmentStart()));
                logger.error(String.format("    Negative strand: %b", allAlignments[i].isNegativeStrand()));
                logger.error(String.format("    Cigar: %s", allAlignments[i].getCigarString()));
                logger.error(String.format("    Mapping quality: %s%n", allAlignments[i].getMappingQuality()));
            }
            throw new StingException(String.format("Read %s mismatches!", read.getReadName()));
        }

        if(++count % 10000 == 0) logger.info(String.format("Processed %d reads", count));

        //logger.info(String.format("validated read %s", read.getReadName()));        

        return 1;
    }

    /**
     * Initial value for reduce.  In this case, validated reads will be counted.
     * @return 0, indicating no reads yet validated.
     */
    @Override
    public Integer reduceInit() { return 0; }

    /**
     * Calculates the number of reads processed.
     * @param value Number of reads processed by this map.
     * @param sum Number of reads processed before this map.
     * @return Number of reads processed up to and including this map.
     */
    @Override
    public Integer reduce(Integer value, Integer sum) {
        return value + sum;
    }

    /**
     * Cleanup.
     * @param result Number of reads processed.
     */
    @Override
    public void onTraversalDone(Integer result) {
        aligner.close();
        super.onTraversalDone(result);
    }

}