ios - 当超过 2 列时，条形图会向上跳跃

Question

我正在处理一个图表，按下按钮时数据集会发生变化。但看起来当我有超过 2 个柱时，图表原点就会发生变化。

两列就可以了:

创建数据集:

private func buildMoodDummyBarData(period: Period) -> [BarChartDataEntry] {

    if period == .week {
        let entry1 = BarChartDataEntry(x: 0, y: 720)
        let entry2 = BarChartDataEntry(x: 1, y: 440)
        let entry3 = BarChartDataEntry(x: 2, y: 0)
        let entry4 = BarChartDataEntry(x: 3, y: 30)
        let entry5 = BarChartDataEntry(x: 4, y: 30)

        return [entry1, entry2, entry3, entry4, entry5]

    } else if period == .month {

        let entry1 = BarChartDataEntry(x: 0, y: 100)
        let entry2 = BarChartDataEntry(x: 1, y: 300)
        let entry3 = BarChartDataEntry(x: 2, y: 50)
        let entry4 = BarChartDataEntry(x: 3, y: 30)
        let entry5 = BarChartDataEntry(x: 4, y: 30)

        return [entry1, entry2, entry3, entry4, entry5]

    } else {

        return []
    }
}

完成构建数据集并更改条形颜色:

func buildMoodBarData(period: Period) -> BarChartData? {

    let entries = buildMoodDummyBarData(period: period)

    let set = BarChartDataSet(values: entries, label: nil)
    set.highlightEnabled = false

    let tempData = BarChartData(dataSet: set) // Just to find max
    let max = tempData.yMax
    let onePercent = max / 100

    var colors = [UIColor]()
    for item in entries {
        let percentValue = item.y / onePercent
        colors.append(setColor(value: percentValue))
    }
    set.colors = colors

    let data = BarChartData(dataSet: set)
    data.setDrawValues(true)
    data.barWidth = 0.72

    return data
}

// barChartView is storyboard outlet
private  func makeMoodBarChart() {

    barChartView.backgroundColor = UIColor.red
    barChartView.chartDescription = nil
    barChartView.leftAxis.enabled = false
    barChartView.rightAxis.enabled = false
    barChartView.legend.enabled = false
    barChartView.xAxis.enabled = false
}

private func updateMoodBarChart(with data: BarChartData) {

    barChartView.data = data
    barChartView.fitBars = false
    barChartView.fitScreen()
}

Answer 1

问题与数据集有关。当我将其替换为以下数据时，问题消失了。我认为出现问题是因为 Y 比例值变化太大。

private func buildMoodDummyBarData(period: Period) -> [BarChartDataEntry] {

    if period == .week {
        let entry1 = BarChartDataEntry(x: 0, y: 10)
        let entry2 = BarChartDataEntry(x: 1, y: 50)
        let entry3 = BarChartDataEntry(x: 2, y: 100)
        let entry4 = BarChartDataEntry(x: 3, y: 20)
        let entry5 = BarChartDataEntry(x: 4, y: 30)

        return [entry1, entry2, entry3, entry4, entry5]

    } else if period == .month {

        let entry1 = BarChartDataEntry(x: 0, y: 100)
        let entry2 = BarChartDataEntry(x: 1, y: 30)
        let entry3 = BarChartDataEntry(x: 2, y: 30)
        let entry4 = BarChartDataEntry(x: 3, y: 20)
        let entry5 = BarChartDataEntry(x: 4, y: 30)

        return [entry1, entry2, entry3, entry4, entry5]

    } else {

        return []
    }
}

这并不意味着两个数据集中的最小值和最大值必须完全相同(20 到 100)，但是如果差异太大(第一个数据集中为 30 到 320，第二个数据集中为 30 到 720)，图表基线变化。

这不是理想的解决方案。