net 总数据中取随机几条数据

                List<string> lstSample = new List<string>();              
                Random rand = new Random();
                List<int> lstRand = new List<int>();
                for (int i = 0; lstRand.Count() < sampleNum; i++)
                {
                    int mRandNum = rand.Next(0, mStageDataCount);
                    if (!lstRand.Contains(mRandNum))
                    {
                        lstRand.Add(mRandNum);
                        lstSample.Add(lstDataAll.ToList()[mRandNum]);
                    }
                }