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V24.1

IChartDataAdapter.GetNumericalValue(Int32, ChartDataMemberType) Method

Returns a data item’s numeric value for a data member of the specified type by the index.

Namespace: DevExpress.XtraCharts

Assembly: DevExpress.XtraCharts.v24.1.dll

NuGet Package: DevExpress.Charts

Declaration

double GetNumericalValue(
    int index,
    ChartDataMemberType dataMember
)

Parameters

Name Type Description
index Int32

A zero-based integer that specifies the item’s position within the collection. If the passed index is negative or exceeds the last available index, an exception is raised.

dataMember ChartDataMemberType

The data member type.

Returns

Type Description
Double

The numeric data item value.

Example

How to: Implement a Custom Chart Data Adapter

This example shows how to create an adapter that loads numeric data to the chart:

using DevExpress.XtraCharts;
using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace CustomDataAdapter {
    public partial class Form1 : Form {
        const long DataItemCount = 100000;
        const int MaxValue = 100;
        const int MinValue = 80;
        Random rand = new Random();
        public Form1() {
            InitializeComponent();

            Series series = new Series("Series", ViewType.Line);
            chartControl1.Series.Add(series);

            List<DataItem> dataItems = new List<DataItem>();
            for (int i = 0; i < DataItemCount; i++) {
                dataItems.Add(new DataItem(i, rand.NextDouble() * (MaxValue - MinValue) + MaxValue));
            }

            series.DataAdapter = new CustomNumericDataAdapter(dataItems);

            ((XYDiagram)chartControl1.Diagram).AxisY.WholeRange.AlwaysShowZeroLevel = false;

        }
    }
    public class DataItem {
        public double Argument { get; }
        public double Value { get; }
        public DataItem(double argument, double value) {
            Argument = argument;
            Value = value;
        }
    }
    public class CustomNumericDataAdapter : ISeriesAdapter {
        readonly IList<DataItem> items;
        public bool DataSorted => true;
        public int ItemsCount => this.items.Count;
        public CustomNumericDataAdapter(IList<DataItem> items) {
            this.items = items;
        }
        event NotifyChartDataChangedEventHandler IChartDataAdapter.DataChanged {
            add { }
            remove { }
        }
        public object Clone() {
            return this;
        }
        public double GetNumericalValue(int index, ChartDataMemberType dataMember) {
            switch (dataMember) {
                case ChartDataMemberType.Argument: return items[index].Argument;
                case ChartDataMemberType.Value: return items[index].Value;
            }
            return double.NaN;
        }
        public object GetSourceObject(int index) {
            return this.items[index];
        }
        public ActualScaleType GetScaleType(ChartDataMemberType dataMember) {
            return ActualScaleType.Numerical;
        }
        public DateTime GetDateTimeValue(int index, ChartDataMemberType dataMember) {
            throw new NotImplementedException();
        }
        public string GetQualitativeValue(int index, ChartDataMemberType dataMember) {
            throw new NotImplementedException();
        }
        public TimeSpan GetTimeSpanValue(int index, ChartDataMemberType dataMember) {
            throw new NotImplementedException();
        }
        public object GetObjectValue(int index, ChartDataMemberType dataMember) {
            throw new NotImplementedException();
        }
    }
}
See Also