# init(xStart:xEnd:y:height:) Creates a rectangle mark with an x interval encoding and a y encoding. ``` nonisolated init(xStart: PlottableValue, xEnd: PlottableValue, y: PlottableValue, height: MarkDimension = .automatic) where X : Plottable, Y : Plottable ``` ## Parameters `xStart` The value plotted with x start. `xEnd` The value plotted with x end. `y` The value plotted with y. `height` The rectangle height. If `height` is not specified, then 70% of the step size will be used. If there is no step size a default height (in pts) will be used. ## Discussion ### Discussion Use this initializer to map the x start, x end and y position to a rectangle for each data element. Optionally, specify the height of the rectangles. The example below omits the optional `height` parameter and uses a number scale starting at (0,0) and ending at (6,6). The rectangle has the coordinates: (2,0), (2,4), (4,4), (4,0). ```swift Chart(data) { RectangleMark( xStart: .value("Rect xStart", 2), xEnd: .value("Rect xEnd", 4), y: .value("Rect Y", 4) ) .opacity(0.2) PointMark( x: .value("X", $0.x), y: .value("Y", $0.y) ) } ```  --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)