def partially_tracked(df, track_ratios):
    """Number of objects tracked between 20 and 80 percent of lifespan."""
    del df  # unused
    return track_ratios[(track_ratios >= 0.2) & (track_ratios < 0.8)].count()
Number of objects tracked between 20 and 80 percent of lifespan.
motmetrics/metrics.py