XySequence edits and combiner

Want a method that will combine XySequences, adding the y-values of identical x-values. Found some other little things to fix/clean first and then helper methods that will help with the combine method.

• Refactor ArrayXySequence.hashCode() to return Objects.has(Arrays.hashCode(xs), Arrays.hashCode(ys)); should yield same result
• Refactor ArrayXySequence.validateSequence() to use only Arrays.equals(this.xs, that.xs); the first test in Arrays.equals() does the redundant first comparison
• Add package-private Sequences.areSimilar(Collection<XySequence>), return boolean; checkState(!coll.isEmpty()); if size == 1, return true; multiple ways to do this; at this point in time, we have total control over the creation of XySequences so any XySequence in the supplied collection can safely be cast to ArrayXySequence; could create a Predicate that stores the first xs array, then stream the collection and use allMatch
• Add Sequences.combine(Collection<XySequence>), returns XySequence; if the sequences areSimilar() combine using MutableXySequence.add(XySequence); else use a stream, flatMap and a toMap collector that will yield a sorted Map<Double, Double> that can then be used to populate a new XySequence.

changed the description

marked the checklist item Refactor ArrayXySequence.hashCode() to return Objects.has(Arrays.hashCode(xs), Arrays.hashCode(ys)); should yield same result as completed

marked the checklist item Refactor ArrayXySequence.validateSequence() to use only Arrays.equals(this.xs, that.xs); the first test in Arrays.equals() does the redundant first comparison as completed

marked the checklist item Add package-private Sequences.areSimilar(Collection<XySequence>), return boolean; checkState(!coll.isEmpty()); if size == 1, return true; multiple ways to do this; at this point in time, we have total control over the creation of XySequences so any XySequence in the supplied collection can safely be cast to ArrayXySequence; could create a Predicate that stores the first xs array, then stream the collection and use allMatch as completed

@pmpowers - Sequences.combine(Collection) should be public or package private?

package private for now

marked the checklist item Add Sequences.combine(Collection<XySequence>), returns XySequence; if the sequences areSimilar() combine using MutableXySequence.add(XySequence); else use a stream, flatMap and a toMap collector that will yield a sorted Map<Double, Double> that can then be used to populate a new XySequence. as completed

Generation of expected results in tests could be cleaned up, currently it's done manually.

mentioned in merge request !93 (merged)

closed via merge request !93 (merged)

mentioned in commit d1cbaa77