rr.io/r/grid/grid.xspline.html" class="external-link">grid::xsplineGrob()</a></code> with four control points each: the endpoints and the two knots. To complement them, several other curves are now available: linear (equivalent to <code>knot.pos = 0</code>), cubic, quintic, sinusoidal, arctangent, and sigmoid, summoned by the new <code>curve_type</code> parameter (which defaults to the x-spline). (The asymptotic functions, arctangent and sigmoid, are compressed according to the new <code>curve_range</code> 