/// <summary>
/// Replaces a random concrete note pitch with a hold note.
/// </summary>
/// <param name="melody"> The candidate melody which contains the bar sequence to operate on. </param>
/// <param name="barIndex"> An index of specific requested bar to operate on. </param>
private protected virtual void ToggleToHoldNoteMutation(MelodyCandidate melody, int?barIndex)
{
// intialize random generator
Random random = new Random();
// fetch the requested bar randomly select one if no specific bar is requested
barIndex = barIndex ?? random.Next(melody.Bars.Count);
IBar selectedBar = melody.Bars[(int)barIndex];
// fetch potential notes for the toggle (filter rest, hold & first notes in bar)
IList <INote> relevantNotes = selectedBar.Notes.Where((note, noteIndex) =>
noteIndex > 0 &&
note.Pitch != NotePitch.RestNote &&
note.Pitch != NotePitch.HoldNote).ToList();
// assure at least one note as found
if (!relevantNotes.Any())
{
return;
}
// fetch a random note from the potential notes found
int randomNoteIndex = random.Next(relevantNotes.Count);
INote selectedNote = relevantNotes[randomNoteIndex];
// get original index of the selected note in the original sequence
int originalNoteIndex = selectedBar.Notes.IndexOf(selectedNote);
// replace selected note with a hold note
INote holdNote = MusicTheoryFactory.CreateNote(NotePitch.HoldNote, selectedNote.Duration);
selectedBar.Notes.RemoveAt(originalNoteIndex);
selectedBar.Notes.Insert(originalNoteIndex, holdNote);
}
/// <summary>
/// Randomly selects two consecutive notes in the given bar, or in a randomly selected
/// bar if <paramref name="barIndex"/> is null, and unifies the two consecutive notes
/// into one note by removing the consecutive note entirely and adding it's
/// duration length to the first note.
/// </summary>
/// <param name="melody"> The candidate melody to operate on.</param>
/// <param name="barIndex"> Index of the bar to do the unification in. If no bar index supplied, then a random bar would be selected. </param>
private protected virtual void DurationUnifyMutation(MelodyCandidate melody, int?barIndex = null)
{
// initialization
INote note1, note2, newNote;
IDuration newDuration;
int note1Index, note2Index;
Random random = new Random();
// if no specific bar has been requested then set it randomly
int selectedBarIndex = barIndex ?? random.Next(melody.Bars.Count);
IBar bar = melody.Bars[selectedBarIndex];
// assure selected bar contains at least two notes
if (bar.Notes.Count < 2)
{
return;
}
// randomly select two consecutive notes from within the selected bar
note1Index = random.Next(1, bar.Notes.Count);
note2Index = note1Index - 1;
note1 = bar.Notes[note1Index];
note2 = bar.Notes[note2Index];
/* create a new note with the pitch of the first note and overall duration
* duration of the sum of the two notes durations */
newDuration = note1.Duration.Add(note2.Duration);
newNote = MusicTheoryFactory.CreateNote(note1.Pitch, newDuration);
// replace the two consecutive note with the new note
bar.Notes.RemoveAt(note1Index);
bar.Notes.Insert(note1Index, newNote);
bar.Notes.RemoveAt(note2Index);
}