vl.markLine({interpolate: 'step-before'})
.data(movies)
.transform(
vl.filter('datum.Running_Time_min != null'),
vl.groupby('Running_Time_min').aggregate(vl.count().as('Count')),
vl.window(vl.sum('Count').as('Cumulative_Sum')).sort(vl.field('Running_Time_min'))
)
.encode(
vl.x().fieldQ('Running_Time_min').title('Duration (min)'),
vl.y().fieldQ('Cumulative_Sum').title('Cumulative Count of Films')
)
.render()