Draw a circle with lineChart

Question

I'm trying to draw a circle using a LineChartView using Charts, I had no trouble doing this with a parabola, but when I try a circle, I get

Error: this application, or a library it uses, has passed an invalid numeric value (NaN, or not-a-number) to CoreGraphics API and this value is being ignored. Please fix this problem.

and

If you want to see the backtrace, please set CG_NUMERICS_SHOW_BACKTRACE environmental variable.

Weird thing is, if I zoom and move through the graph to the right I can see part of the circle looking like this this.

On my viewDidLoad() I got

chartView.delegate = self

    chartView.chartDescription?.enabled = false

    chartView.dragEnabled = true
    chartView.setScaleEnabled(true)
    chartView.pinchZoomEnabled = true
    chartView.highlightPerDragEnabled = true

    chartView.backgroundColor = .white

    chartView.legend.enabled = false


    let xAxis = chartView.xAxis
    xAxis.labelFont = .systemFont(ofSize: 10, weight: .light)
    xAxis.labelTextColor = UIColor.black
    xAxis.drawAxisLineEnabled = true
    xAxis.drawGridLinesEnabled = true
    xAxis.gridLineWidth = 1
    xAxis.gridLineDashLengths = [1,1]
    xAxis.axisMaximum = 100
    xAxis.axisMinimum = -100

    xAxis.granularity = 0.5
    let leftAxis = chartView.leftAxis
    leftAxis.labelPosition = .insideChart
    leftAxis.labelFont = .systemFont(ofSize: 12, weight: .light)
    leftAxis.drawGridLinesEnabled = true
    leftAxis.gridLineWidth = 1
    leftAxis.gridLineDashLengths = [1,1]
    leftAxis.granularityEnabled = true
    leftAxis.axisMinimum = -100
    leftAxis.axisMaximum = 100
    leftAxis.granularity = 0.5
    leftAxis.yOffset = -9
    leftAxis.labelTextColor = UIColor.black

    chartView.xAxis.gridLineDashLengths = [1,1]
    chartView.rightAxis.enabled = false

    chartView.legend.form = .line


    setDataCount()
    //chartView.animate(xAxisDuration: 2.5)

And this is basically what I have on my function

func setDataCount() {

    let yVal1 = (-100...100).map {

        return ChartDataEntry(x: Double($0), y: sqrt(100 - pow(Double($0), 2)))

    }

    let yVal2 = (-100...100).map {
       return ChartDataEntry(x: Double($0), y: sqrt(100 - pow(Double($0), 2)) * -1)
    }

    let set1 = LineChartDataSet(values: yVal1, label: "Top")
     //set1.axisDependency = .left
     set1.setColor(UIColor.red)
     set1.drawCirclesEnabled = false
     set1.lineWidth = 2
    set1.mode = .cubicBezier

    let set2 = LineChartDataSet(values: yVal2, label: "Bottom")
    set2.setColor(UIColor.black)
    set2.drawCirclesEnabled = false
    set2.lineWidth = 2

    set2.mode = .cubicBezier

    let data = LineChartData(dataSets: [set1,set2])

    data.setValueFont(.systemFont(ofSize: 9))
    data.setDrawValues(false)
    chartView.data = data
}

I'm still learning and experimenting with graphs, so I really don't get where the problem is, how can I show correctly the circle in my LineChartView?

It's impossible to calculate square root from negative values. It's the reason why you get NaN value. So, you need to change your formula. — AlexSmet, Nov 06 '18 at 06:11
yeah I just figured out it has to do with the range I'm passing to the map, it has to be the diameter of said circle, thanks — Zoila Garza, Nov 06 '18 at 06:24

score 0 · Answer 1 · edited Apr 20 '20 at 13:36

0

change drawCirclesEnabled property of data set.

set1.drawCirclesEnabled = true
set2.drawCirclesEnabled = true

edited Apr 20 '20 at 13:36

David Buck

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answered Apr 20 '20 at 12:59

Vijay Chaudhary

1
2

Draw a circle with lineChart

1 Answers1