iOS Charts 3 - Align X Labels (dates) with plots

Question

I have found a similar question on here, but the answer did not help me. I think due to my data structure.

I have an array made up of individual arrays, each for its own line in the chart. this is then made up of multiple structs for the plot points of that line.

My issue is that values/lines are correct, but are not aligning correctly with the dates. In the example below. the dates start at 3rd May and end 8th May. Please help

here is my code

struct chartPoint {
let date:String
var total:Double
let exercise:String
}
 var sets:[[chartPoint]] = []

func setupLineChart() {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd"
    var dataSets:[LineChartDataSet] = []
    var color:[UIColor] = [UIColor.red,UIColor.blue, UIColor.green,UIColor.red,UIColor.red,UIColor.red,UIColor.red]
    for i in sets { //Array of array of structs
        let sort = i.sorted { // sort the internal array by date
            item1, item2 in
            let date1 = dateFormatter.date(from:item1.date)
            let date2 =  dateFormatter.date(from:item2.date)
            return date1!.compare(date2!) == ComparisonResult.orderedAscending
        }
        var dataEntries: [ChartDataEntry] = []
        for stat in 0...(sort.count - 1) {
            let date = dateFormatter.date(from:sort[stat].date)
            let timeIntervalForDate: TimeInterval = date!.timeIntervalSince1970
            let dataEntry = ChartDataEntry(x: Double(timeIntervalForDate), y: sort[stat].total)
            dataEntries.append(dataEntry)
            if stat == (sort.count - 1){
                let chartDataSet = LineChartDataSet(values: dataEntries, label: "\(sort[stat].exercise)")
                chartDataSet.setCircleColor(color[stat])
                chartDataSet.setColor(color[stat], alpha: 1.0)

                chartDataSet.drawValuesEnabled = true
                dataSets.append(chartDataSet)
                startChart(dataSets: dataSets)
            }
        }
    }

}

func startChart(dataSets:[LineChartDataSet]){
    testLineChartView.animate(xAxisDuration: 0.7, yAxisDuration: 0.7)
    testLineChartView.dragEnabled = true
    testLineChartView.legend.form = .circle
    testLineChartView.drawGridBackgroundEnabled = false

    let xaxis = testLineChartView.xAxis
    xaxis.valueFormatter = axisFormatDelegate
    xaxis.labelCount = dataSets.count
    xaxis.granularityEnabled = true
    xaxis.granularity = 1.0
    xaxis.centerAxisLabelsEnabled = true
    xaxis.avoidFirstLastClippingEnabled = true
    xaxis.drawLimitLinesBehindDataEnabled = true

    let rightAxis = testLineChartView.rightAxis
    rightAxis.enabled = false

    let leftAxis = testLineChartView.leftAxis
    leftAxis.drawZeroLineEnabled = true
    leftAxis.drawGridLinesEnabled = true
    axisFormatDelegate = self
    testLineChartView.delegate = self

    let chartData = LineChartData(dataSets: dataSets)
    testLineChartView.data = chartData
    testLineChartView.chartDescription?.text = ""
}

extension ChartViewController: IAxisValueFormatter {
func stringForValue(_ value: Double, axis: AxisBase?) -> String {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "dd MMM"
    let date = Date(timeIntervalSince1970: value)
    return dateFormatter.string(from: date)
}

}

score 1 · Accepted Answer · answered May 09 '17 at 19:42

1

I am using dates on the x-axis as well in one of my projects and I simply changed each date to a string and passed an array of string values to an IndexAxisValueFormatter.

 testLineChartView.xAxis.valueFormatter = IndexAxisValueFormatter(values: xvalues)

If this is not what you are looking for, can you show a sample of what "sets" includes? Then I will be able to run your code.

answered May 09 '17 at 19:42

DevB2F

4,674
4
36
60

Is this not the same as ( let xaxis = testLineChartView.xAxis xaxis.valueFormatter = axisFormatDelegate )? – ThundercatChris May 10 '17 at 13:12
I have updated my code to show what set is. it basically an array with arrays of plot points, made up of arrays of structs. that way one line can have several plot points inside an array and another line can have its own. I hope that makes sense – ThundercatChris May 10 '17 at 13:16
I have also tried using an array of date strings (I think thats what you have suggested), but again they are misaligned. I dont think the strings are the issue. its the offset – ThundercatChris May 10 '17 at 14:13

score 0 · Answer 2 · edited May 23 '17 at 12:34

0

Here is another thread I started with an issue around a single value not showing. It includes the code that also fixed this.

I think the main point being

 xaxis.forceLabelsEnabled = true

iOS Charts - single values not showing Swift

edited May 23 '17 at 12:34

Community

1
1

answered May 19 '17 at 14:44

ThundercatChris

481
6
25

iOS Charts 3 - Align X Labels (dates) with plots

2 Answers2