Charts - ScatterChart 1:1 Axis Scale

Question

I want to plot some x and y data inside a ScatterChartView, but I can't seem to figure out how I can set my x- and y-axis to be scaled equally.

I have tried to use the height and width of the chart to calculate both axes min and max values independently, but that was quite messy and did not lead to any good result.

Do you have any suggestions? Have I overlooked anything inside the documentation?

Underneath is my SwiftUI view I'm using as my scatter plot.

import SwiftUI
import Charts

struct ScatterPlot: UIViewRepresentable {
    typealias UIViewType = ScatterChartView

    private let plot = ScatterChartView()

    func makeUIView(context: Context) -> ScatterChartView {
        setUpPlot()
        return plot
    }

    func updateUIView(_ uiView: ScatterChartView, context: Context) {}

    private func setUpPlot() {
        plot.rightAxis.enabled = false
    
        let dataSets = [getScatterPlotDataSet()]
        let data = ScatterChartData(dataSets: dataSets)
    
        plot.data = data
    }

    private func getScatterPlotDataSet() -> ScatterChartDataSet {
        let entries: [ChartDataEntry] = [ChartDataEntry(x: 0, y: 0), ChartDataEntry(x: 1, y: 1)]
        let dataSet = ScatterChartDataSet(entries: entries)
    
        return dataSet
    }
}

Thanks in advance.

Answer 1

I try to calculate the width and height ratio and get this result

please note I using storyboard for this example, you need to check are you get correct chart width and height in your swiftUI code

    chart.rightAxis.enabled = false
    
    let width = chart.frame.width
    let height = chart.frame.height
    
    let maxValue: Double = 1.0
    
    chart.xAxis.granularity = 0.5
    chart.leftAxis.granularity = 0.5
    
    chart.leftAxis.axisMaximum = maxValue
    chart.xAxis.axisMinimum = 0
    chart.leftAxis.axisMinimum = 0
    chart.xAxis.axisMaximum = Double(width / height) * maxValue