Interpolate

The line interpolation method to use for line and area marks. One of the following:

• "linear": piecewise linear segments, as in a polyline.
• "linear-closed": close the linear segments to form a polygon.
• "step": alternate between horizontal and vertical segments, as in a step function.
• "step-before": alternate between vertical and horizontal segments, as in a step function.
• "step-after": alternate between horizontal and vertical segments, as in a step function.
• "basis": a B-spline, with control point duplication on the ends.
• "basis-open": an open B-spline; may not intersect the start or end.
• "basis-closed": a closed B-spline, as in a loop.
• "cardinal": a Cardinal spline, with control point duplication on the ends.
• "cardinal-open": an open Cardinal spline; may not intersect the start or end, but will intersect other control points.
• "cardinal-closed": a closed Cardinal spline, as in a loop.
• "bundle": equivalent to basis, except the tension parameter is used to straighten the spline.
• "monotone": cubic interpolation that preserves monotonicity in y.

The line interpolation method for the error band. One of the following:

• "linear": piecewise linear segments, as in a polyline.
• "linear-closed": close the linear segments to form a polygon.
• "step": a piecewise constant function (a step function) consisting of alternating horizontal and vertical lines. The y-value changes at the midpoint of each pair of adjacent x-values.
• "step-before": a piecewise constant function (a step function) consisting of alternating horizontal and vertical lines. The y-value changes before the x-value.
• "step-after": a piecewise constant function (a step function) consisting of alternating horizontal and vertical lines. The y-value changes after the x-value.
• "basis": a B-spline, with control point duplication on the ends.
• "basis-open": an open B-spline; may not intersect the start or end.
• "basis-closed": a closed B-spline, as in a loop.
• "cardinal": a Cardinal spline, with control point duplication on the ends.
• "cardinal-open": an open Cardinal spline; may not intersect the start or end, but will intersect other control points.
• "cardinal-closed": a closed Cardinal spline, as in a loop.
• "bundle": equivalent to basis, except the tension parameter is used to straighten the spline.
• "monotone": cubic interpolation that preserves monotonicity in y.