area.lineX0() area.lineY0() Returns a new line generator that has this area generator’s current defined accessor, curve and context. The line’s x-accessor is this area’s x0-accessor, and the line’s y-accessor is this area’s y0-accessor.

area.defined([defined]) If defined is specified, sets the defined accessor to the specified function or boolean and returns this area generator. If defined is not specified, returns the current defined accessor, which defaults to: function defined() { return true; } The default accessor thus assumes that the input data is always defined. When an area is generated, the defined accessor will be invoked for each element in the input data array, being passed the element d, the index i, and the

area.curve([curve]) If curve is specified, sets the curve factory and returns this area generator. If curve is not specified, returns the current curve factory, which defaults to curveLinear.

area.context([context]) If context is specified, sets the context and returns this area generator. If context is not specified, returns the current context, which defaults to null. If the context is not null, then the generated area is rendered to this context as a sequence of path method calls. Otherwise, a path data string representing the generated area is returned.

area(data) Generates an area for the given array of data. Depending on this area generator’s associated curve, the given input data may need to be sorted by x-value before being passed to the area generator. If the area generator has a context, then the area is rendered to this context as a sequence of path method calls and this function returns void. Otherwise, a path data string is returned.

arc.startAngle([angle]) If angle is specified, sets the start angle to the specified function or number and returns this arc generator. If angle is not specified, returns the current start angle accessor, which defaults to: function startAngle(d) { return d.startAngle; } The angle is specified in radians, with 0 at -y (12 o’clock) and positive angles proceeding clockwise. If |endAngle - startAngle| ≥ τ, a complete circle or annulus is generated rather than a sector.

arc.padRadius([radius]) If radius is specified, sets the pad radius to the specified function or number and returns this arc generator. If radius is not specified, returns the current pad radius accessor, which defaults to null, indicating that the pad radius should be automatically computed as sqrt(innerRadius * innerRadius + outerRadius * outerRadius). The pad radius determines the fixed linear distance separating adjacent arcs, defined as padRadius * padAngle.

arc.padAngle([angle]) If angle is specified, sets the pad angle to the specified function or number and returns this arc generator. If angle is not specified, returns the current pad angle accessor, which defaults to: function padAngle() { return d && d.padAngle; } The pad angle is converted to a fixed linear distance separating adjacent arcs, defined as padRadius * padAngle. This distance is subtracted equally from the start and end of the arc. If the arc forms a complete circle o

arc.outerRadius([radius]) If radius is specified, sets the outer radius to the specified function or number and returns this arc generator. If radius is not specified, returns the current outer radius accessor, which defaults to: function outerRadius(d) { return d.outerRadius; } Specifying the outer radius as a function is useful for constructing a coxcomb or polar bar chart, often in conjunction with a sqrt scale. More commonly, a constant outer radius is used for a pie or donut chart. If

arc.innerRadius([radius]) If radius is specified, sets the inner radius to the specified function or number and returns this arc generator. If radius is not specified, returns the current inner radius accessor, which defaults to: function innerRadius(d) { return d.innerRadius; } Specifying the inner radius as a function is useful for constructing a stacked polar bar chart, often in conjunction with a sqrt scale. More commonly, a constant inner radius is used for a donut or pie chart. If th