C# chart控件实现扇形图的一种方式

/// <summary>
/// 绘制扇形图
/// </summary>
/// <param name="count"></param>
private void PainAlam(int count)
{
    Hashtable ht = new Hashtable();
    //第一次遍历所有警报，存入到哈希表里面，value设置为1。value为已出现报警的次数
    for (int i = 0; i < count; i++)
    {
        var item = DgvReportData.Rows[i].Cells["alarmname"].Value; //每次访问DgvReportData第i行第alarmname的列的值
        if (ht.Contains(item))
        {
            //如果该警报已经存在则改变对应的value值 + 1
            int tmp = (int)ht[key: item];
            ht[item] = 1 + tmp;
        }
        else
            ht.Add(item, 1);
    }

    string[] x = new string[count];
    double[] y = new double[count];

    //第二次遍历哈希表，给数据源赋值。value/count就是报警出现次数的百分比
    ICollection key = ht.Keys;
    int sub = 0;
    foreach (string item in key)
    {
        int value = (int)ht[key: item];
        y[sub] = value;
        string percent = ((value*100)/(count)).ToString();
        x[sub] = item + " 占 " + percent + "%";
        sub++;
    }
    //将两个数据源绑定到chart1
    chtAlam.Series["Series1"].Points.DataBindXY(x, y);
}