The walk-forward section of a SweepResult, present exactly when the
sweep was submitted with SweepWalkForward.
paramDrift absent is not zero. The field is omitted whenever the figure
could not be computed — fewer than two folds finished, or no stored grid to
place the winners on — and zero is itself a meaningful reading there (winners
that never moved), so a placeholder would be indistinguishable from perfect
stability.
The walk-forward section of a SweepResult, present exactly when the sweep was submitted with SweepWalkForward.
paramDriftabsent is not zero. The field is omitted whenever the figure could not be computed — fewer than two folds finished, or no stored grid to place the winners on — and zero is itself a meaningful reading there (winners that never moved), so a placeholder would be indistinguishable from perfect stability.