private Optional<CoverageCoordAxisBuilder> subsetValues(double minValue, double maxValue, int stride) { if (axis.getSpacing() == CoverageCoordAxis.Spacing.discontiguousInterval) return subsetValuesDiscontinuous(minValue, maxValue, stride); double lower = axis.isAscending() ? Math.min(minValue, maxValue) : Math.max(minValue, maxValue); double upper = axis.isAscending() ? Math.max(minValue, maxValue) : Math.min(minValue, maxValue); int minIndex = findCoordElement(lower, false); int maxIndex = findCoordElement(upper, false); if (minIndex >= axis.getNcoords()) return Optional.empty(String.format("no points in subset: lower %f > end %f", lower, axis.getEndValue())); if (maxIndex < 0) return Optional.empty(String.format("no points in subset: upper %f < start %f", upper, axis.getStartValue())); if (minIndex < 0) minIndex = 0; if (maxIndex >= axis.getNcoords()) maxIndex = axis.getNcoords() - 1; int count = maxIndex - minIndex + 1; if (count <= 0) throw new IllegalArgumentException("no points in subset"); try { return Optional.of(subsetByIndex(new Range(minIndex, maxIndex, stride))); } catch (InvalidRangeException e) { return Optional.empty(e.getMessage()); } }