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Next generation sequencing (NGS/HTS) reads.
/*
ngs-reads Next generation sequencing (NGS/HTS) reads.
Copyright (c) 2014 National Marrow Donor Program (NMDP)
This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 3 of the License, or (at
your option) any later version.
This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation,
Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> http://www.gnu.org/licenses/lgpl.html
*/
package org.nmdp.ngs.reads;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import java.io.Flushable;
import java.io.IOException;
import java.util.Iterator;
import org.apache.commons.math3.distribution.IntegerDistribution;
import org.apache.commons.math3.distribution.RealDistribution;
import org.apache.commons.math3.distribution.UniformIntegerDistribution;
import org.apache.commons.math3.random.RandomGenerator;
import org.biojava.bio.program.fastq.Fastq;
import org.biojava.bio.program.fastq.FastqBuilder;
import org.biojava.bio.program.fastq.FastqVariant;
import org.biojava.bio.program.fastq.FastqWriter;
import org.biojava.bio.seq.DNATools;
import org.biojava.bio.seq.Sequence;
import org.biojava.bio.symbol.IllegalSymbolException;
import org.biojava.bio.symbol.Symbol;
import org.biojava.bio.symbol.SymbolList;
/**
* Generate next generation sequencing (NGS/HTS) reads.
*/
public final class GenerateReads implements Runnable {
/** Reference. */
private final Sequence reference;
/** FASTQ variant. */
private final FastqVariant variant;
/** Random. */
private final RandomGenerator random;
/** Location distribution. */
private final IntegerDistribution location;
/** Length distribution. */
private final RealDistribution length;
/** Quality strategy. */
private final QualityStrategy quality;
/** Coverage strategy. */
private final CoverageStrategy coverage;
/** Mutation rate. */
private final double mutationRate;
/** Mutation strategy. */
private final MutationStrategy mutation;
/** Appendable. */
private final Appendable appendable;
/** FASTQ writer. */
private final FastqWriter writer;
/**
* Generate next generation sequencing (NGS/HTS) reads.
*
* @param reference reference, must not be null
* @param variant FASTQ variant, must not be null
* @param random random, must not be null
* @param length length distribution, must not be null
* @param quality quality strategy, must not be null
* @param coverage coverage strategy, must not be null
* @param mutationRate mutation rate, must be between 0.0 and 1.0, inclusive
* @param mutation mutation strategy, must not be null
* @param appendable appendable, must not be null
* @param writer FASTQ writer, must not be null
*/
public GenerateReads(final Sequence reference,
final FastqVariant variant,
final RandomGenerator random,
final RealDistribution length,
final QualityStrategy quality,
final CoverageStrategy coverage,
final double mutationRate,
final MutationStrategy mutation,
final Appendable appendable,
final FastqWriter writer) {
checkNotNull(reference, "reference must not be null");
checkNotNull(variant, "variant must not be null");
checkNotNull(random, "random must not be null");
checkNotNull(length, "length must not be null");
checkNotNull(quality, "quality must not be null");
checkNotNull(coverage, "coverage must not be null");
checkArgument(mutationRate >= 0.0d, "mutationRate must be greater than or equal to 0.0d");
checkArgument(mutationRate <= 1.0d, "mutationRate must be less than or equal to 1.0d");
checkNotNull(mutation, "mutation must not be null");
checkNotNull(appendable, "appendable must not be null");
checkNotNull(writer, "writer must not be null");
this.reference = reference;
this.variant = variant;
this.random = random;
this.length = length;
this.quality = quality;
this.coverage = coverage;
this.mutationRate = mutationRate;
this.mutation = mutation;
this.appendable = appendable;
this.writer = writer;
int flanking = (int) (length.getNumericalMean() + length.getNumericalVariance());
location = new UniformIntegerDistribution(this.random, 1 - flanking, this.reference.length() + flanking);
}
@Override
public void run() {
int count = 0;
// while coverage not met
while (!coverage.evaluate(reference)) {
// sample location
int start = location.sample();
int end = start + (int) length.sample();
// if valid location
if (start < reference.length() && end > 1) {
write(start, end, count);
}
count++;
}
}
private void write(final int start, final int end, final int count) {
// truncate on both ends
int s = Math.max(1, start);
int e = Math.min(reference.length() + 1, end);
SymbolList read = reference.subList(s, e - 1);
// mutate and build sequence
StringBuilder sequence = new StringBuilder();
for (Iterator i = read.iterator(); i.hasNext(); ) {
Symbol symbol = i.next();
if (random.nextDouble() < mutationRate) {
for (Iterator j = mutation.mutate(symbol).iterator(); j.hasNext(); ) {
Symbol mutated = j.next();
try {
sequence.append(DNATools.dnaToken(mutated));
}
catch (IllegalSymbolException ex) {
// ignore
}
}
}
else {
try {
sequence.append(DNATools.dnaToken(symbol));
}
catch (IllegalSymbolException ex) {
// ignore
}
}
}
// apply quality scores
StringBuilder qualityScores = new StringBuilder();
for (int i = 0, size = sequence.length(); i < size; i++) {
double qualityScore = quality.qualityScore(i, size);
qualityScores.append(variant.quality(Math.max(Math.min((int) qualityScore, variant.maximumQualityScore()), variant.minimumQualityScore())));
}
// write fastq
Fastq fastq = new FastqBuilder()
.withVariant(variant)
.withDescription(reference.getName() + "-" + count)
.withSequence(sequence.toString())
.withQuality(qualityScores.toString())
.build();
try {
writer.append(appendable, fastq);
if (appendable instanceof Flushable) {
((Flushable) appendable).flush();
}
}
catch (IOException ex) {
// ignore
}
// update coverage
coverage.add(reference, s, Math.min(reference.length() + 1, s + read.length()));
}
}
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