/**
* Extract a slice of $length sequences starting at position $offset from the Collection.
*
* If $length is null it returns all sequences from $offset to the end of the Collection.
* Keys have to be preserved by this method. Calling this method will only return the
* selected slice and NOT change the sequences contained in the collection slice is called on.
*
* @param int $offset
* @param int $length
* @return array
*/
public function slice($offset, $length = null)
{
$sequences = array();
$index = array_slice($this->sequenceFile->getSequenceIndex(), $offset, $length, true);
foreach ($index as $indexEntry => $value) {
$sequences[$indexEntry] = $this->sequenceFile->readSequence($indexEntry);
}
return $sequences;
}
/**
* Unset an offset.
*
* @param mixed $offset
*/
public function offsetUnset($offset)
{
return $this->sequenceFile->deleteSequence($offset);
}
