设置矩形宽度在列表c# WPF的项目

如何设置矩形的宽度，通过在c#中通过用户控件划分列表中的Items的数量，使用WPF必须在代码后面，而不是使用Xaml:

public partial class UserControl1 : UserControl
{
    private List<Color> colours;
    private int Highest;
    private int Lowest;
    private int Median;
    public int Width {get; set;}
    private Data mydata;
    public Data data 
    { 
        get
        {
            return mydata;
        }
        set
        {
            mydata = value;
            BindData();
        }
    }

    public UserControl1()
    {
        colours = new List<Color>() { Colors.Red, Colors.White, Colors.Blue};
        InitializeComponent();
        if (Width == 0)
        {
            Width = 300;
        }
    }
    private void BindData()
    {
        //work out rectangle width
        Highest = Convert.ToInt32(mydata.Values.Max());
        Lowest = Convert.ToInt32(mydata.Values.Min());
        Median = Convert.ToInt32(mydata.Values.Average());
        foreach (double item in mydata.Values)
        {
            //create rectangle of width specified
            SetWidth();
        }
    }
    private void SetWidth()
    {
        //divide number of items in list by total to define Width
    }
    private Color GetColourFromValue(int totalNumber)
    {
        var numOfColours = colours.Count;
        if (totalNumber >= numOfColours)
        {
            return colours[totalNumber % numOfColours];
        }
        return colours[totalNumber]; 
    }
    private Color GetGradeColour(byte itemNumber, byte totalNumberItems, Color ItemColour)
    {
        byte multipler = (byte)(200 / totalNumberItems);
        byte a = (byte)((itemNumber + 1) * multipler);
        return Color.FromArgb(a, ItemColour.R, ItemColour.G, ItemColour.B);
    }
    private Rectangle CreateRectangle(double Value, int Width, Color ItemColor)//double value, width)
    {
        //create rectangle
        var rectangle = new Rectangle()
        {
            //Fill = new SolidColorBrush(ItemColor)
        };
        //give rectangle width
        return rectangle;
    }
}