# init(x:yStart:yEnd:width:) Creates a rectangle mark that plots values on x and has a fixed y interval. ``` nonisolated init(x: PlottableValue, yStart: CGFloat? = nil, yEnd: CGFloat? = nil, width: MarkDimension = .automatic) where X : Plottable ``` ## Discussion - x: The value plotted with x. - width: The rectangle width. If `width` is not specified, then 70% of the step size will be used. If there is no step size a default width (in pts) will be used. - yStart: The y start position. If `yStart` is `nil` then the rectangle will start at the leading edge of the plotting area. - yEnd: The y end position. If `yEnd` is `nil` then the rectangle will end at the trailing edge of the plotting area. ### Discussion Use this initializer to map an x position to a rectangle for each data element. Optionally, specify the width, yStart position, or yEnd positions of the rectangles. The example below omits the optional `width`, `yStart`, and `yEnd` parameters and uses a number scale starting at (0,0) and ending at (6,6). The rectangle has the coordinates: (0,0), (0,6), (3,6), (3,0). ```swift Chart(data) { RectangleMark( x: .value("Rect X", 3) ) .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)