+
+ /**
+ * Removes a specified number of positions from the start of a ranges list.
+ * For example, could be used to adjust cds ranges to allow for an incomplete
+ * start codon. Subranges are removed completely, or their start positions
+ * adjusted, until the required number of positions has been removed from the
+ * range. Reverse strand ranges are supported. The input array is not
+ * modified.
+ *
+ * @param removeCount
+ * @param ranges
+ * an array of [start, end, start, end...] positions
+ * @return a new array with the first removeCount positions removed
+ */
+ public static int[] removeStartPositions(int removeCount,
+ final int[] ranges)
+ {
+ if (removeCount <= 0)
+ {
+ return ranges;
+ }
+
+ int[] copy = Arrays.copyOf(ranges, ranges.length);
+ int sxpos = -1;
+ int cdspos = 0;
+ for (int x = 0; x < copy.length && sxpos == -1; x += 2)
+ {
+ cdspos += Math.abs(copy[x + 1] - copy[x]) + 1;
+ if (removeCount < cdspos)
+ {
+ /*
+ * we have removed enough, time to finish
+ */
+ sxpos = x;
+
+ /*
+ * increment start of first exon, or decrement if reverse strand
+ */
+ if (copy[x] <= copy[x + 1])
+ {
+ copy[x] = copy[x + 1] - cdspos + removeCount + 1;
+ }
+ else
+ {
+ copy[x] = copy[x + 1] + cdspos - removeCount - 1;
+ }
+ break;
+ }
+ }
+
+ if (sxpos > 0)
+ {
+ /*
+ * we dropped at least one entire sub-range - compact the array
+ */
+ int[] nxon = new int[copy.length - sxpos];
+ System.arraycopy(copy, sxpos, nxon, 0, copy.length - sxpos);
+ return nxon;
+ }
+ return copy;
+ }
+
+ /**
+ * Removes the specified number of positions from the given ranges. Provided
+ * to allow a stop codon to be stripped from a CDS sequence so that it matches
+ * the peptide translation length.
+ *
+ * @param positions
+ * @param ranges
+ * a list of (single) [start, end] ranges
+ * @return
+ */
+ public static void removeEndPositions(int positions,
+ List<int[]> ranges)
+ {
+ int toRemove = positions;
+ Iterator<int[]> it = new ReverseListIterator<>(ranges);
+ while (toRemove > 0)
+ {
+ int[] endRange = it.next();
+ if (endRange.length != 2)
+ {
+ /*
+ * not coded for [start1, end1, start2, end2, ...]
+ */
+ System.err
+ .println("MappingUtils.removeEndPositions doesn't handle multiple ranges");
+ return;
+ }
+
+ int length = endRange[1] - endRange[0] + 1;
+ if (length <= 0)
+ {
+ /*
+ * not coded for a reverse strand range (end < start)
+ */
+ System.err
+ .println("MappingUtils.removeEndPositions doesn't handle reverse strand");
+ return;
+ }
+ if (length > toRemove)
+ {
+ endRange[1] -= toRemove;
+ toRemove = 0;
+ }
+ else
+ {
+ toRemove -= length;
+ it.remove();
+ }
+ }
+ }