Relative Strength Index

Relative Strength Index (RSI) indicator for FinancialChart is a momentum oscillator, which measures velocity and magnitude of price movements. It compares the upward movements in closing price of an asset to the downward movements over a trading period, and intends to determine strength or weakness of a stock. It fluctuates between 0 and 100. The stocks with strong positive changes have a higher RSI than the stocks with strong negative changes.

It finds application in comparing the magnitude of recent gains to recent losses, to determine the overbought and oversold conditions of an asset. Stocks are considered overbought when RSI is above 70, and oversold when below 30.

Notice that the given code snippet uses a class DataService.cs. To see the code, refer to Average True Range. In addition, the sample creates an instance of the RSI class to work with Relative Strength Index.

DataService.vb
DataService.cs

DataService.vb

Public Class DataService
    Private _companies As New List(Of Company)()
    Private _cache As New Dictionary(Of String, List(Of Quote))()

    Private Sub New()
        _companies.Add(New Company() With {
            Key.Symbol = "box",
            Key.Name = "Box Inc"
        })
        _companies.Add(New Company() With {
            Key.Symbol = "fb",
            Key.Name = "Facebook"
        })
    End Sub

    Public Function GetCompanies() As List(Of Company)
        Return _companies
    End Function

    Public Function GetSymbolData(symbol As String) As List(Of Quote)
        If Not _cache.Keys.Contains(symbol) Then
            Dim path As String = String.Format("FinancialChartExplorer.Resources.{0}.json", symbol)
            Dim stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(path)
            Dim ser = New DataContractJsonSerializer(GetType(Quote()))
            Dim data = DirectCast(ser.ReadObject(stream), Quote())
            _cache.Add(symbol, data.ToList())
        End If

        Return _cache(symbol)
    End Function

    Shared _ds As DataService
    Public Shared Function GetService() As DataService
        If _ds Is Nothing Then
            _ds = New DataService()
        End If
        Return _ds
    End Function
End Class

DataService.cs

public class DataService
{
    List<Company> _companies = new List<Company>();
    Dictionary<string, List<Quote>> _cache = new Dictionary<string, List<Quote>>();

    private DataService()
    {
        _companies.Add(new Company() { Symbol = "box", Name = "Box Inc" });
        _companies.Add(new Company() { Symbol = "fb", Name = "Facebook" });
    }

    public List<Company> GetCompanies()
    {
        return _companies;
    }

    public List<Quote> GetSymbolData(string symbol)
    {
        if (!_cache.Keys.Contains(symbol))
        {
            string path = string.Format("FinancialChartExplorer.Resources.{0}.json", symbol);
            var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(path);
            var ser = new DataContractJsonSerializer(typeof(Quote[]));
            var data = (Quote[])ser.ReadObject(stream);
            _cache.Add(symbol, data.ToList());
        }

        return _cache[symbol];
    }

    static DataService _ds;
    public static DataService GetService()
    {
        if (_ds == null)
            _ds = new DataService();
        return _ds;
    }
}

Visual Basic
C#

Visual Basic

Partial Public Class Indicators
    Inherits UserControl

    Private dataService As DataService = DataService.GetService()
    Private rsi As New RSI() With {
        Key.SeriesName = "RSI"
    }

    Public Sub New()
        InitializeComponent()
    End Sub

    Public ReadOnly Property Data() As List(Of Quote)
        Get
            Return dataService.GetSymbolData("box")
        End Get
    End Property

    Public ReadOnly Property IndicatorType() As List(Of String)
        Get
            Return New List(Of String)() From {
                "Relative Strength Index"
            }
        End Get
    End Property

    Private Sub OnIndicatorTypeSelectionChanged(sender As Object, e As SelectionChangedEventArgs)
        Dim ser As FinancialSeries = Nothing
        If cbIndicatorType.SelectedIndex = 0 Then
            ser = rsi
        End If


        If ser IsNot Nothing AndAlso Not indicatorChart.Series.Contains(ser) Then
            indicatorChart.BeginUpdate()
            indicatorChart.Series.Clear()
            indicatorChart.Series.Add(ser)
            indicatorChart.EndUpdate()
        End If
    End Sub

    Private Sub OnFinancialChartRendered(sender As Object, e As C1.WPF.Chart.RenderEventArgs)
        If indicatorChart IsNot Nothing Then
            indicatorChart.AxisX.Min = DirectCast(financialChart.AxisX, IAxis).GetMin()
            indicatorChart.AxisX.Max = DirectCast(financialChart.AxisX, IAxis).GetMax()
        End If
    End Sub
End Class

public partial class Indicators : UserControl
{

    DataService dataService = DataService.GetService();
    RSI rsi = new RSI() { SeriesName = "RSI" };

    public Indicators()
    {
        InitializeComponent();
    }

    public List<Quote> Data
    {
        get
        {
            return dataService.GetSymbolData("box");
        }
    }

    public List<string> IndicatorType
    {
        get
        {
            return new List<string>()
            {
                "Relative Strength Index",
            };
        }
    }

    void OnIndicatorTypeSelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        FinancialSeries ser = null;
        if (cbIndicatorType.SelectedIndex == 0)
            ser = rsi;


        if (ser != null && !indicatorChart.Series.Contains(ser))
        {
            indicatorChart.BeginUpdate();
            indicatorChart.Series.Clear();
            indicatorChart.Series.Add(ser);
            indicatorChart.EndUpdate();
        }
    }

    void OnFinancialChartRendered(object sender, C1.WPF.Chart.RenderEventArgs e)
    {
        if (indicatorChart != null)
        {
            indicatorChart.AxisX.Min = ((IAxis)financialChart.AxisX).GetMin();
            indicatorChart.AxisX.Max = ((IAxis)financialChart.AxisX).GetMax();
        }
    }
}