# init(xStart:xEnd:yStart:yEnd:) Creates a rectangle mark with x and y interval encodings. ``` nonisolated init(xStart: PlottableValue, xEnd: PlottableValue, yStart: PlottableValue, yEnd: PlottableValue) where X : Plottable, Y : Plottable ``` ## Parameters `xStart` The value plotted with x start. `xEnd` The value plotted with x end. `yStart` The value plotted with y start. `yEnd` The value plotted with y end. ## Discussion ### Discussion Use this initializer to map the x start, x end, y start, and y end position to a rectangle for each data element. The example below uses a number scale starting at (0,0) and ending at (6,6). The rectangle has the coordinates: (2,2), (2,4), (4,4), (4,2). ```swift Chart(data) { RectangleMark( xStart: .value("Rect xStart", 2), xEnd: .value("Rect xEnd", 4), yStart: .value("Rect yStart", 2), yEnd: .value("Rect yEnd", 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)