/**
* Will hard clip every soft clipped bases in the read.
*
* @return a new read without the soft clipped bases
*/
private GATKSAMRecord hardClipSoftClippedBases() {
if (read.isEmpty()) return read;
int readIndex = 0;
int cutLeft = -1; // first position to hard clip (inclusive)
int cutRight = -1; // first position to hard clip (inclusive)
boolean rightTail =
false; // trigger to stop clipping the left tail and start cutting the right tail
for (CigarElement cigarElement : read.getCigar().getCigarElements()) {
if (cigarElement.getOperator() == CigarOperator.SOFT_CLIP) {
if (rightTail) {
cutRight = readIndex;
} else {
cutLeft = readIndex + cigarElement.getLength() - 1;
}
} else if (cigarElement.getOperator() != CigarOperator.HARD_CLIP) rightTail = true;
if (cigarElement.getOperator().consumesReadBases()) readIndex += cigarElement.getLength();
}
// It is extremely important that we cut the end first otherwise the read coordinates change.
if (cutRight >= 0) this.addOp(new ClippingOp(cutRight, read.getReadLength() - 1));
if (cutLeft >= 0) this.addOp(new ClippingOp(0, cutLeft));
return clipRead(ClippingRepresentation.HARDCLIP_BASES);
}
/**
* Generic functionality to hard clip a read, used internally by
* hardClipByReferenceCoordinatesLeftTail and hardClipByReferenceCoordinatesRightTail. Should not
* be used directly.
*
* <p>Note, it REQUIRES you to give the directionality of your hard clip (i.e. whether you're
* clipping the left of right tail) by specifying either refStart < 0 or refStop < 0.
*
* @param refStart first base to clip (inclusive)
* @param refStop last base to clip (inclusive)
* @return a new read, without the clipped bases
*/
@Requires({
"!read.getReadUnmappedFlag()",
"refStart < 0 || refStop < 0"
}) // can't handle unmapped reads, as we're using reference coordinates to clip
protected GATKSAMRecord hardClipByReferenceCoordinates(int refStart, int refStop) {
if (read.isEmpty()) return read;
int start;
int stop;
// Determine the read coordinate to start and stop hard clipping
if (refStart < 0) {
if (refStop < 0)
throw new ReviewedStingException(
"Only one of refStart or refStop must be < 0, not both ("
+ refStart
+ ", "
+ refStop
+ ")");
start = 0;
stop =
ReadUtils.getReadCoordinateForReferenceCoordinate(
read, refStop, ReadUtils.ClippingTail.LEFT_TAIL);
} else {
if (refStop >= 0)
throw new ReviewedStingException(
"Either refStart or refStop must be < 0 (" + refStart + ", " + refStop + ")");
start =
ReadUtils.getReadCoordinateForReferenceCoordinate(
read, refStart, ReadUtils.ClippingTail.RIGHT_TAIL);
stop = read.getReadLength() - 1;
}
if (start < 0 || stop > read.getReadLength() - 1)
throw new ReviewedStingException(
"Trying to clip before the start or after the end of a read");
if (start > stop)
throw new ReviewedStingException(
String.format(
"START (%d) > (%d) STOP -- this should never happen, please check read: %s (CIGAR: %s)",
start, stop, read, read.getCigarString()));
if (start > 0 && stop < read.getReadLength() - 1)
throw new ReviewedStingException(
String.format(
"Trying to clip the middle of the read: start %d, stop %d, cigar: %s",
start, stop, read.getCigarString()));
this.addOp(new ClippingOp(start, stop));
GATKSAMRecord clippedRead = clipRead(ClippingRepresentation.HARDCLIP_BASES);
this.ops = null;
return clippedRead;
}
public static List<GATKSAMRecord> hardClipToRegion(
final List<GATKSAMRecord> reads, final int refStart, final int refStop) {
final List<GATKSAMRecord> returnList = new ArrayList<GATKSAMRecord>(reads.size());
for (final GATKSAMRecord read : reads) {
final GATKSAMRecord clippedRead = hardClipToRegion(read, refStart, refStop);
if (!clippedRead.isEmpty()) {
returnList.add(clippedRead);
}
}
return returnList;
}
/**
* Hard clips a read using read coordinates.
*
* @param start the first base to clip (inclusive)
* @param stop the last base to clip (inclusive)
* @return a new read, without the clipped bases
*/
@Requires({
"start >= 0 && stop <= read.getReadLength() - 1", // start and stop have to be within the read
"start == 0 || stop == read.getReadLength() - 1"
}) // cannot clip the middle of the read
private GATKSAMRecord hardClipByReadCoordinates(int start, int stop) {
if (read.isEmpty() || (start == 0 && stop == read.getReadLength() - 1))
return GATKSAMRecord.emptyRead(read);
this.addOp(new ClippingOp(start, stop));
return clipRead(ClippingRepresentation.HARDCLIP_BASES);
}
/**
* Hard clips any leading insertions in the read. Only looks at the beginning of the read, not the
* end.
*
* @return a new read without leading insertions
*/
private GATKSAMRecord hardClipLeadingInsertions() {
if (read.isEmpty()) return read;
for (CigarElement cigarElement : read.getCigar().getCigarElements()) {
if (cigarElement.getOperator() != CigarOperator.HARD_CLIP
&& cigarElement.getOperator() != CigarOperator.SOFT_CLIP
&& cigarElement.getOperator() != CigarOperator.INSERTION) break;
else if (cigarElement.getOperator() == CigarOperator.INSERTION)
this.addOp(new ClippingOp(0, cigarElement.getLength() - 1));
}
return clipRead(ClippingRepresentation.HARDCLIP_BASES);
}
/**
* Hard clips away soft clipped bases that are below the given quality threshold
*
* @param read the read
* @param minQual the mininum base quality score to revert the base (inclusive)
* @return a new read without low quality soft clipped bases
*/
public static GATKSAMRecord hardClipLowQualitySoftClips(GATKSAMRecord read, byte minQual) {
int nLeadingSoftClips = read.getAlignmentStart() - read.getSoftStart();
if (read.isEmpty() || nLeadingSoftClips > read.getReadLength())
return GATKSAMRecord.emptyRead(read);
byte[] quals = read.getBaseQualities(EventType.BASE_SUBSTITUTION);
int left = -1;
if (nLeadingSoftClips > 0) {
for (int i = nLeadingSoftClips - 1; i >= 0; i--) {
if (quals[i] >= minQual) left = i;
else break;
}
}
int right = -1;
int nTailingSoftClips = read.getSoftEnd() - read.getAlignmentEnd();
if (nTailingSoftClips > 0) {
for (int i = read.getReadLength() - nTailingSoftClips; i < read.getReadLength(); i++) {
if (quals[i] >= minQual) right = i;
else break;
}
}
GATKSAMRecord clippedRead = read;
if (right >= 0
&& right + 1
< clippedRead
.getReadLength()) // only clip if there are softclipped bases (right >= 0) and the
// first high quality soft clip is not the last base (right+1 <
// readlength)
clippedRead =
hardClipByReadCoordinates(
clippedRead,
right + 1,
clippedRead.getReadLength()
- 1); // first we hard clip the low quality soft clips on the right tail
if (left >= 0
&& left - 1
> 0) // only clip if there are softclipped bases (left >= 0) and the first high quality
// soft clip is not the last base (left-1 > 0)
clippedRead =
hardClipByReadCoordinates(
clippedRead,
0,
left - 1); // then we hard clip the low quality soft clips on the left tail
return clippedRead;
}
/**
* Hard clips both tails of a read. Left tail goes from the beginning to the 'left' coordinate
* (inclusive) Right tail goes from the 'right' coordinate (inclusive) until the end of the read
*
* @param left the coordinate of the last base to be clipped in the left tail (inclusive)
* @param right the coordinate of the first base to be clipped in the right tail (inclusive)
* @return a new read, without the clipped bases
*/
@Requires({
"left <= right", // tails cannot overlap
"left >= read.getAlignmentStart()", // coordinate has to be within the mapped read
"right <= read.getAlignmentEnd()"
}) // coordinate has to be within the mapped read
private GATKSAMRecord hardClipBothEndsByReferenceCoordinates(int left, int right) {
if (read.isEmpty() || left == right) return GATKSAMRecord.emptyRead(read);
GATKSAMRecord leftTailRead = hardClipByReferenceCoordinates(right, -1);
// after clipping one tail, it is possible that the consequent hard clipping of adjacent
// deletions
// make the left cut index no longer part of the read. In that case, clip the read entirely.
if (left > leftTailRead.getAlignmentEnd()) return GATKSAMRecord.emptyRead(read);
ReadClipper clipper = new ReadClipper(leftTailRead);
return clipper.hardClipByReferenceCoordinatesLeftTail(left);
}
/**
* Clips a read according to ops and the chosen algorithm.
*
* @param algorithm What mode of clipping do you want to apply for the stacked operations.
* @return the read with the clipping applied.
*/
public GATKSAMRecord clipRead(ClippingRepresentation algorithm) {
if (ops == null) return getRead();
GATKSAMRecord clippedRead = read;
for (ClippingOp op : getOps()) {
final int readLength = clippedRead.getReadLength();
// check if the clipped read can still be clipped in the range requested
if (op.start < readLength) {
ClippingOp fixedOperation = op;
if (op.stop >= readLength) fixedOperation = new ClippingOp(op.start, readLength - 1);
clippedRead = fixedOperation.apply(algorithm, clippedRead);
}
}
wasClipped = true;
ops.clear();
if (clippedRead.isEmpty()) return GATKSAMRecord.emptyRead(clippedRead);
return clippedRead;
}
/**
* Clips any contiguous tail (left, right or both) with base quality lower than lowQual using the
* desired algorithm.
*
* <p>This function will look for low quality tails and hard clip them away. A low quality tail
* ends when a base has base quality greater than lowQual.
*
* @param algorithm the algorithm to use (HardClip, SoftClip, Write N's,...)
* @param lowQual every base quality lower than or equal to this in the tail of the read will be
* hard clipped
* @return a new read without low quality tails
*/
private GATKSAMRecord clipLowQualEnds(ClippingRepresentation algorithm, byte lowQual) {
if (read.isEmpty()) return read;
final byte[] quals = read.getBaseQualities();
final int readLength = read.getReadLength();
int leftClipIndex = 0;
int rightClipIndex = readLength - 1;
// check how far we can clip both sides
while (rightClipIndex >= 0 && quals[rightClipIndex] <= lowQual) rightClipIndex--;
while (leftClipIndex < readLength && quals[leftClipIndex] <= lowQual) leftClipIndex++;
// if the entire read should be clipped, then return an empty read.
if (leftClipIndex > rightClipIndex) return GATKSAMRecord.emptyRead(read);
if (rightClipIndex < readLength - 1) {
this.addOp(new ClippingOp(rightClipIndex + 1, readLength - 1));
}
if (leftClipIndex > 0) {
this.addOp(new ClippingOp(0, leftClipIndex - 1));
}
return this.clipRead(algorithm);
}
/**
* Turns soft clipped bases into matches
*
* @return a new read with every soft clip turned into a match
*/
private GATKSAMRecord revertSoftClippedBases() {
if (read.isEmpty()) return read;
this.addOp(new ClippingOp(0, 0));
return this.clipRead(ClippingRepresentation.REVERT_SOFTCLIPPED_BASES);
}
