C# List.Where方法代码示例

        public LogisticMap(double mu, double r0, double rmax, double dr)
        {
            mapData.ChartType = SeriesChartType.Point ;
            mapData.MarkerSize = 1;
            mapData.MarkerColor = Color.Black;

            int numberOfThreadsInMap =1 ;
            List<double> activeThreadValues;
            double eps = .005;
            for(double r = r0; r < rmax; r+= dr ){
                activeThreadValues = new List<double>();
                Func<double, double> log = i => r * i * (1 - Math.Pow(i, mu));
                for (int i = 150; i < 260; i++) {
                    var A = new Sequence(log,	.2).GetElementAt(i);
                    if (A > double.MaxValue || A < double.MinValue) {
                        break;
                    }
                    if (activeThreadValues.Where(j => j < A + eps && j > A - eps).Count() == 0)
                        activeThreadValues.Add(A);
                    mapData.Points.AddXY(r, A);
                }
                if (activeThreadValues.Count > numberOfThreadsInMap) {
                    Console.WriteLine("Bifurcation point: " + r.ToString() + " " + activeThreadValues.Count.ToString() + " threads.");
                    numberOfThreadsInMap = activeThreadValues.Count();
                    eps /= numberOfThreadsInMap;
                }
            }
        }

        static void Main(string[] args)
        {
            int totalCount = 3;
            List<Student> listStudent = new List<Student>();
            for (int i = 0; i < 3; i++)
            {
                Student objStudent = new Student();
                Console.Write("Please enter the Student ID: ");
                objStudent.StudentId = Int32.Parse(Console.ReadLine());
                Console.Write("Please enter the Student Name: ");
                objStudent.Name = Console.ReadLine();
                listStudent.Add(objStudent);
            }

            //Query to get by name - only first occurence
            //Student student = listStudent.First(x => x.Name == "Karthik");
            Student student = listStudent.FirstOrDefault(x => x.Name == "Karthik");

            if(student != null)
                Console.WriteLine(string.Format("ID: {0} Name: {1}", student.StudentId, student.Name));

            //Query to get by name - all occurences
            //IEnumerable<Student> stdList = listStudent.Where(x => x.Name == "Karthik");
            IEnumerable<Student> stdList = listStudent.Where(x => x.StudentId >= 20);
            foreach (var student1 in stdList)
            {
                Console.WriteLine(string.Format("ID: {0} Name: {1}", student1.StudentId, student1.Name));
            }

            listStudent.Sort((std1, std2) => std1.Name.CompareTo(std2.Name));
            listStudent.ForEach(x=>Console.WriteLine(x.Name));
        }

 private  List<CalendarItem> MergeItems(List<CalendarItem> newItems, List<CalendarItem> fromRepo)
 {
     var result = new List<CalendarItem>();
     var newModels = newItems.Except(fromRepo, new CalendarItemEqualityComparer()).ToList();
     var updatet = fromRepo.Except(newModels,new CalendarItemEqualityComparer()).ToList();
     updatet.ForEach(x =>
     {
         var model = newItems.FirstOrDefault(y => y.Id == x.Id);
         if (model != null)
         {
             model.SyncStatus.CalenadCalendarItemStatus = IsModified(model, x)
                 ? CalendarItemStatus.Updated
                 : CalendarItemStatus.Unmodified;
             result.Add(model);
         }
     });
     var deleted = fromRepo.Where(x => x.Start.Date >= DateTime.Now.Date).Except(newItems).Except(updatet);
     newModels.ForEach(x => x.SyncStatus.CalenadCalendarItemStatus = CalendarItemStatus.New);
     deleted.ForEach(x =>
     {
         x.SyncStatus.CalenadCalendarItemStatus = CalendarItemStatus.Deleted;
         result.Add(x);
     });
     result.AddRange(newModels);
     return result.OrderBy(x => x.Start).ToList();
 }

        private static void LambdaExpression(List<Student> students)
        {
            List<Student> selectedStudents = students.Where(s => s.GroupNumber == 2)
                                                   .OrderBy(s => s.FirstName)
                                                   .ToList();

            selectedStudents.ForEach(s => Console.WriteLine("First name: {0}, Group number: {1}", s.FirstName, s.GroupNumber));
        }

        /// <summary>Returns numeric indicator of market activity. Higher value means higher activity (i.e. lot of trades with higher volume).</summary>
        /// <param name="tradeHistory">Description of last executed trades of exchange</param>
        /// <param name="now">Current local time of the exchange</param>
        /// <returns>Coeficient in [0.0, 1.0] where 0.0 means totally peacefull market, 1.0 is wild.</returns>
        internal static float GetMadness(List<Trade> tradeHistory, DateTime now)
        {
            //Trades of past 4mins
            List<Trade> trades = tradeHistory.Where(trade => trade.Time >= now.AddSeconds(-240)).ToList();
            if (!trades.Any())
            {
                return 0.0f;
            }

            //Group by time, so that single trade with big volume doesn't look like many trades
            var groupped = new Dictionary<string, Trade>();
            foreach (var trade in trades)
            {
                var key = trade.timestamp + "_" + trade.type;
                if (!groupped.ContainsKey(key))
                {
                    groupped.Add(key, new Trade(trade.price, trade.amount, trade.Type));
                }
                else
                {
                    groupped[key].amount += trade.amount;
                    if (TradeType.BUY == trade.Type && trade.amount > groupped[key].amount)
                        groupped[key].amount = trade.amount;
                    else if (TradeType.SELL == trade.Type && trade.amount < groupped[key].amount)
                        groupped[key].amount = trade.amount;
                }
            }

            //        Console.WriteLine("DEBUG: {0} trades in past 90sec, {1} groupped by time", tradeHistory.Count, groupped.Count);

            const int MIN_TRADES = 4;
            const int MAX_TRADES = 14;
            float intenseCoef;
            if (groupped.Count < MIN_TRADES)        //Too few trades
                intenseCoef = 0.0f;
            else if (groupped.Count >= MAX_TRADES)  //Too many trades
                intenseCoef = 1.0f;
            else
                intenseCoef = (float)(groupped.Count - MIN_TRADES) / (MAX_TRADES - MIN_TRADES);

            const double MIN_AVG_VOLUME = 20;
            const double MAX_AVG_VOLUME = 50;
            float volumeCoef;
            double avgVolume = groupped.Sum(trade => trade.Value.amount) / groupped.Count;
            //        Console.WriteLine("DEBUG: avgVolume={0}", avgVolume);
            if (avgVolume < MIN_AVG_VOLUME)
                volumeCoef = 0.0f;
            else if (avgVolume >= MAX_AVG_VOLUME)
                volumeCoef = 1.0f;
            else
                volumeCoef = (float)((avgVolume - MIN_AVG_VOLUME) / (MAX_AVG_VOLUME - MIN_AVG_VOLUME));

            //        Console.WriteLine("DEBUG: intensityCoef={0}, volumeCoef={1}", intenseCoef, volumeCoef);

            //Average of volume and frequency coeficients
            return (intenseCoef + volumeCoef) / 2;
        }

        private static void Expression(List<Student> students)
        {
            var selectedStudents = students.Where(s => s.Group.DepartmentName.Equals("Mathematics"))
                                           .ToList();

            foreach (var student in selectedStudents)
            {
                Console.WriteLine("Name: {0}, Department: {1}", student.FirstName + " " + student.LastName, student.Group.DepartmentName);
            }
        }

        private static void Expression(List<Student> students)
        {
            var selectedStudents = students.Where(s => s.Marks.Count > 0 && s.Marks.Contains(6))
                                    .Select(s => new 
                                    {
                                        FullName = s.FirstName + " " + s.LastName,
                                        Marks = s.MarksPrint()
                                    });

            foreach (var student in selectedStudents)
            {
                Console.WriteLine("{0} {1}", student.FullName, student.Marks);
            }
        }

        private static void Main()
        {
            List<Student> list = new List<Student>();

            for (int i = 0; i < 20; i++)
            {
                Student student = new Student(GenerateRandom.Text(10), GenerateRandom.Text(10));
                student.Age = GenerateRandom.Number(15, 35);

                list.Add(student);
            }

            Console.WriteLine("\nAll:\n");
            list.ForEach(x => Console.WriteLine(x));

            Console.WriteLine("\nFilterd 1:\n");
            var sorted1 = list.Where(x => x.Age >= 18 && x.Age <= 24)
                              .Select(x => new
                              {
                                  FirstName = x.FirstName,
                                  LastName = x.LastName,
                                  Age = x.Age
                              }).ToList();

            sorted1.ForEach(x => Console.WriteLine(x.FirstName + " " + x.LastName + " " + x.Age));

            Console.WriteLine("\nFilterd 2:\n");
            var sorted2 = from s in list
                          where s.Age >= 18 && s.Age <= 24
                          select new
                          {
                              FirstName = s.FirstName,
                              LastName = s.LastName,
                              Age = s.Age
                          };

            foreach (var x in sorted2)
            {
                Console.WriteLine(x.FirstName + " " + x.LastName + " " + x.Age);
            }
        }

        private static void Expression(List<Student> students)
        {
            var selectedStudents = students.Where(s => s.Fn.ToString().Substring(s.Fn.ToString().Length - 2, 2) == "06")
                                    .Select(s => new
                                    {
                                        Fn = s.Fn,
                                        Marks = s.Marks
                                    });

            foreach (var student in selectedStudents)
            {
                Console.Write(student.Fn + ": ");

                foreach (var mark in student.Marks)
                {
                    Console.Write("{0} ", mark);    
                }

                Console.WriteLine();
            }
        }

        private WeatherInfo AggregateInternal(List<WeatherInfo> weatherInfos)
        {
            var weatherInfo = new WeatherInfo();

            var existingWeatherInfos = weatherInfos.Where(p => p != null).ToList();

            weatherInfo.Country = existingWeatherInfos.GetOneResult(info => info.Country != null, info => info.Country);
            weatherInfo.Description = existingWeatherInfos.GetOneResult(info => info.Description != null, info => info.Description);
            weatherInfo.Elevation = existingWeatherInfos.GetOneResult(info => info.Elevation != null, info => info.Elevation);
            weatherInfo.RelativeHumidity = existingWeatherInfos.GetOneResult(info => info.RelativeHumidity != null, info => info.RelativeHumidity);
            weatherInfo.WindDirection = existingWeatherInfos.GetOneResult(info => info.WindDirection != null, info => info.WindDirection);

            var latititudes = existingWeatherInfos.GetMultipleResults(p => p.Latitude.HasValue, p => p.Latitude);
            weatherInfo.Latitude = latititudes.Any() ? latititudes.Average() : null;

            var longitudes = existingWeatherInfos.GetMultipleResults(p => p.Longitude.HasValue, p => p.Longitude);
            weatherInfo.Longitude = longitudes.Any() ? longitudes.Average() : null;

            var pressuresInMb = existingWeatherInfos.GetMultipleResults(p => p.PressureMb.HasValue, p => p.PressureMb);
            weatherInfo.PressureMb = pressuresInMb.Any() ? MathExtensions.Floor(pressuresInMb.Average()) : null;

            var temperaturesCelcius = existingWeatherInfos.GetMultipleResults(p => p.TemperatureCelcius.HasValue, p => p.TemperatureCelcius);
            weatherInfo.TemperatureCelcius = temperaturesCelcius.Any() ? temperaturesCelcius.Average() : null;

            var visibilityDistances = existingWeatherInfos.GetMultipleResults(p => p.VisibilityDistance.HasValue, p => p.VisibilityDistance);
            weatherInfo.VisibilityDistance = visibilityDistances.Any() ? visibilityDistances.Average() : null;

            var windAngles = existingWeatherInfos.GetMultipleResults(p => p.WindAngle.HasValue, p => p.WindAngle);
            weatherInfo.WindAngle = windAngles.Any() ? MathExtensions.Floor(windAngles.Average()) : null;

            var windSpeedsKph = existingWeatherInfos.GetMultipleResults(p => p.WindSpeedKph.HasValue, p => p.WindSpeedKph);
            weatherInfo.WindSpeedKph = windSpeedsKph.Any() ? windSpeedsKph.Average() : null;

            var windSpeedsMs = existingWeatherInfos.GetMultipleResults(p => p.WindSpeedMs.HasValue, p => p.WindSpeedMs);
            weatherInfo.WindSpeedMs = windSpeedsMs.Any() ? windSpeedsMs.Average() : null;

            return weatherInfo;
        }

        /// <summary>
        /// 消费数据分析
        /// </summary>
        /// <returns></returns>
        bool cosumeRecordAnalysis()
        {
            this._IsRunning = true;
            bool res = true;
            try
            {
                bool canStart = false;
                TimeSpan tsNow = new TimeSpan(DateTime.Now.Hour, DateTime.Now.Minute, DateTime.Now.Second);
                foreach (TimeSpan item in this._ListCollectSpan)
                {
                    TimeSpan tsEnd = new TimeSpan();
                    if (item.Hours == 23)
                    {
                        tsEnd = new TimeSpan(23, 59, 59);
                    }
                    else
                    {
                        tsEnd = new TimeSpan(item.Hours + 1, item.Minutes, 0);
                    }

                    if (tsNow > item && tsNow < tsEnd)
                    {
                        canStart = true;
                        break;
                    }
                }
                if (!canStart)
                {
                    this._IsRunning = false;
                    return false;
                }

                //消费机最后同步时间
                DateTime dtMacSync = DateTime.MinValue;
                //找出消费机主档信息，检查是否全部收数完毕，是则进行平数处理，否则不操作
                #region 找出消费机主档信息，检查是否全部收数完毕，是则进行平数处理，否则不操作

                List<ConsumeMachineMaster_cmm_Info> listMachineInfos = this._IConsumeMachineBL.SearchRecords(new ConsumeMachineMaster_cmm_Info()
                    {
                        cmm_cStatus = Common.DefineConstantValue.ConsumeMachineStatus.Using.ToString(),
                    });
                if (listMachineInfos == null)
                {
                    this._IsRunning = false;
                    return false;
                }
                else
                {
                    if (listMachineInfos != null && listMachineInfos.Count > 0)
                    {
                        if (listMachineInfos != null && listMachineInfos.Count > 0)
                        {
                            dtMacSync = listMachineInfos[0].cmm_dLastAccessTime;
                        }
                    }

                    List<ConsumeMachineMaster_cmm_Info> listUnSyncMachineInfos = listMachineInfos.Where(x =>
                          x.cmm_dLastAccessTime.Hour != dtMacSync.Hour).ToList();
                    if (listUnSyncMachineInfos != null && listUnSyncMachineInfos.Count > 0)
                    {
                        this._IsRunning = false;
                        return false;
                    }

                    List<ConsumeMachineMaster_cmm_Info> listUnConnMachineInfos = listMachineInfos.Where(x =>
                        x.cmm_lIsActive == true
                        && x.cmm_lLastAccessRes == false
                        ).ToList();
                    if (listUnConnMachineInfos == null || (listUnConnMachineInfos != null && listUnConnMachineInfos.Count > 0))
                    {
                        this._IsRunning = false;
                        return false;
                    }
                }

                #endregion

                //就餐时段
                #region 学生真实就餐时段列表
                List<CodeMaster_cmt_Info> listMealTimeSpan = this._ICodeMasterBL.SearchRecords(new CodeMaster_cmt_Info()
                {
                    cmt_cKey1 = Common.DefineConstantValue.CodeMasterDefine.KEY1_MealTimeSpan
                });
                if (listMealTimeSpan == null || (listMealTimeSpan != null && listMealTimeSpan.Count < 1))
                {
                    this._IsRunning = false;
                    return false;
                }
                #endregion

                //定餐时段
                #region 学生定餐设置生成时间列表

                List<CodeMaster_cmt_Info> listBookingMealTimeSpan = this._ICodeMasterBL.SearchRecords(new CodeMaster_cmt_Info()
                {
                    cmt_cKey1 = Common.DefineConstantValue.CodeMasterDefine.KEY1_BWListUploadInterval
//.........这里部分代码省略.........

        /// <summary>
        /// 显示子窗体
        /// </summary>
        /// <param name="sender">发送显示请求的按钮或其他控件</param>
        /// <param name="dpnlContainer">显示容器</param>
        /// <param name="strTabName">卡位位置</param>
        /// <param name="strTabName">显示卡位位置</param>
        public void ShowSubForm(object sender, DockPanel dpnlContainer, string strTabName, DockState state)
        {
            string strFormName = string.Empty;

            MenuItem itemMenu = sender as MenuItem;
            if (itemMenu != null)
            {
                strFormName = (itemMenu.Tag as Sys_FormMaster_fom_Info).fom_cExePath;
            }
            else
            {
                ToolStripButton itemBtn = sender as ToolStripButton;
                if (itemBtn != null)
                {
                    strFormName = (itemBtn.Tag as Sys_FormMaster_fom_Info).fom_cExePath;
                }
            }

            if (!string.IsNullOrEmpty(strFormName))
            {
                if (!string.IsNullOrEmpty(strFormName))
                {
                    BaseForm frmTarget = GetFormIn(strFormName);

                    frmTarget.EditState = this.EditState;
                    frmTarget.BaseParam = this.BaseParam;
                    frmTarget.UserInformation = this.UserInformation;

                    if (!string.IsNullOrEmpty(strTabName))
                    {
                        frmTarget.TabText = strTabName;
                    }

                    if (frmTarget == null)
                    {
                        ShowErrorMessage("生成子窗体异常，请联系管理员。");
                    }
                    else
                    {
                        //var tmpList = dpnlContainer.Contents.Where(x => x.DockHandler.TabText == frmTarget.TabText).ToList();
                        var tmpList = dpnlContainer.Contents.Where(x => x.DockHandler.Form.Name == frmTarget.Name).ToList();
                        if (tmpList != null && tmpList.Count < 1)
                        {
                            frmTarget.BaseDockPanel = dpnlContainer;
                            frmTarget.Show(dpnlContainer, state);
                        }
                        else if (tmpList != null && tmpList.Count > 0)//當使用相同窗體不同編輯模式時，Form相同，需要外加編輯狀態屬性判斷是否已被打開該窗體
                        {
                            List<BaseForm> listCompForm = new List<BaseForm>();
                            foreach (var panItem in tmpList)
                            {
                                BaseForm bsTarget = panItem.DockHandler.Form as BaseForm;
                                if (bsTarget != null)
                                {
                                    listCompForm.Add(bsTarget);
                                }
                            }

                            var listTmp = listCompForm.Where(x => x.EditState == this.EditState).ToList();
                            if (listTmp != null && listTmp.Count < 1)
                            {
                                frmTarget.BaseDockPanel = dpnlContainer;
                                frmTarget.Show(dpnlContainer, state);
                            }
                            else if (listTmp != null && listTmp.Count > 0)
                            {
                                listTmp[0].DockHandler.Activate();
                            }
                        }
                    }
                }
                else
                {
                    ShowErrorMessage("发送显示请求的对象没有携带窗口信息，请联系管理员。");
                }
            }
            else
            {
                ShowErrorMessage("发送显示请求的对象有误，请联系管理员。");
            }
        }

        public static IEnumerable<ExigoService.Calendar> GetCalendars(GetCalendarsRequest request)
        {
            var context = Exigo.ODataCalendars();
            var corporateCalendarContext = Exigo.OData();
            var calendars = new List<Calendar>();
            var cacheKey = "GetCalendars/{0}/{1}".FormatWith(request.CustomerID ?? 0, request.IncludeCalendarSubscriptions);
            var cache = (HttpContext.Current != null) ? HttpContext.Current.Cache : null;

            // Check the cache to see if we've already made this call recently
            if (cache == null || cache[cacheKey] == null)
            {
                GlobalUtilities.RunAsyncTasks(

                    // Add the customer's personal calendars
                    () =>
                    {
                        if (request.CustomerID != null)
                        {
                            var apiCalendars = context.Calendars
                                .Where(c => c.CustomerID == (int)request.CustomerID)
                                .ToList();
                            foreach (var apiCalendar in apiCalendars)
                            {
                                calendars.Add((ExigoService.Calendar)apiCalendar);
                            }
                        }
                    },

                    // Include the customer's calendar subscriptions if applicable
                    () =>
                    {
                        if (request.CustomerID != null && request.IncludeCalendarSubscriptions)
                        {
                            var calendarSubscriptions = GetCustomerCalendarSubscriptions((int)request.CustomerID);
                            var calendarSubscriptionsIDs = calendarSubscriptions.Select(c => c.CalendarID).ToList();

                            if (calendarSubscriptionsIDs.Count > 0)
                            {
                                var apiCalendars = context.Calendars
                                    .Where(calendarSubscriptionsIDs.ToOrExpression<CalendarContext.Calendar, Guid>("CalendarID"))
                                    .ToList();
                                foreach (var apiCalendar in apiCalendars)
                                {
                                    calendars.Add((ExigoService.Calendar)apiCalendar);
                                }
                            }
                        }
                    },

                    // Include any additional requested calendars
                    () =>
                    {
                        if (request.CalendarIDs != null && request.CalendarIDs.Count() > 0)
                        {
                            var apiCalendars = context.Calendars
                                .Where(request.CalendarIDs.ToList().ToOrExpression<CalendarContext.Calendar, Guid>("CalendarID"))
                                .ToList();
                            foreach (var apiCalendar in apiCalendars)
                            {
                                calendars.Add((ExigoService.Calendar)apiCalendar);
                            }
                        }
                    }
                );

                // If we asked for a specific customer's calendars, and none of the calendars belong to that customer, create a default calendar and add it to the collection.
                if (request.CustomerID != null && calendars.Where(c => c.CustomerID == (int)request.CustomerID).Count() == 0)
                {
                    var defaultCalendar = CreateDefaultCalendar((int)request.CustomerID);
                    calendars.Add(defaultCalendar);
                }

                if (cache != null)
                {
                    cache.Insert(cacheKey, calendars,
                        null,
                        DateTime.Now.AddMinutes(5),
                        Cache.NoSlidingExpiration,
                        CacheItemPriority.Normal,
                        null);
                }
            }
            else
            {
                calendars = (List<ExigoService.Calendar>)cache[cacheKey];
            }

            // Return the calendars
            foreach (var calendar in calendars)
            {
                yield return calendar;
            }
        }

 private static void Expression(List<Student> students)
 {
     List<Student> selectedStudents = students.Where(s => s.Tel.Substring(0, s.Tel.IndexOf('/')) == "02").ToList();
     selectedStudents.ForEach(student => Console.WriteLine("{0} {1} {2}", student.FirstName, student.LastName, student.Tel));
 }

        //根據事業單位綁定區域
        private void BindcboMachineBigArea(string description)
        {
            var allarea = MasterBLLFactory.GetBLL<IAreaMasterBL>(MasterBLLFactory.AreaMaster).SearchRecords(new AreaMaster_amr_Info());

            List<AreaMaster_amr_Info> alldescription = new List<AreaMaster_amr_Info>();

            foreach (AreaMaster_amr_Info item in allarea)
            {
                alldescription.Add(item);

            }

            alldescription = alldescription.Where(d => d.amr_cPublicInstitution.Trim().ToUpper() == description.ToUpper().Trim()).ToList();

            cboMachineBigArea.DisplayMember = "amr_cAreaName";
            cboMachineBigArea.ValueMember = "amr_cRecordID";
            cboMachineBigArea.DataSource = alldescription;

            cboMachineBigArea.SelectedIndex = -1;
        }