德爾福：我如何將TDateTime四捨五入到最接近的秒，分鐘，五分鐘等？

Question

在Delphi中是否存在一個將TDateTime值舍入爲最接近的秒，最近的小時，最近的5分鐘，最近的半小時等的例程？

更新：

Gabr提供了一個答案。有一些小的錯誤，可能是由於缺乏完整的測試;-)

我清理了一下，測試它，這裏的最終版本（？）：

function RoundDateTimeToNearestInterval(vTime : TDateTime; vInterval : TDateTime = 5*60/SecsPerDay) : TDateTime; 
var 
    vTimeSec,vIntSec,vRoundedSec : int64; 
begin 
    //Rounds to nearest 5-minute by default 
    vTimeSec := round(vTime * SecsPerDay); 
    vIntSec := round(vInterval * SecsPerDay); 

    if vIntSec = 0 then exit(vTimeSec/SecsPerDay); 

    vRoundedSec := round(vTimeSec/vIntSec) * vIntSec; 

    Result := vRoundedSec/SecsPerDay; 
end; 

Answer 1

類似的東西（完全未經測試，直接在瀏覽器中編寫）：

function RoundToNearest(time, interval: TDateTime): TDateTime; 
var 
    time_sec, int_sec, rounded_sec: int64; 
begin 
    time_sec := Round(time * SecsPerDay); 
    int_sec := Round(interval * SecsPerDay); 
    rounded_sec := (time_sec div int_sec) * int_sec; 
    if (rounded_sec + int_sec - time_sec) - (time_sec - rounded_sec) then 
    rounded_sec := rounded_sec + time+sec; 
    Result := rounded_sec/SecsPerDay; 
end; 

該代碼假定您希望以二次精度舍入。毫秒被扔掉。

Answer 2

這是未經測試的代碼，精度可調。

Type 
    TTimeDef = (tdSeconds, tdMinutes, tdHours, tdDays) 

function ToClosest(input : TDateTime; TimeDef : TTimeDef ; Range : Integer) : TDateTime 
var 
    Coeff : Double; 
RInteger : Integer; 
DRInteger : Integer; 
begin 
    case TimeDef of 
    tdSeconds : Coeff := SecsPerDay; 
    tdMinutes : Coeff := MinsPerDay; 
    tdHours : Coeff := MinsPerDay/60; 
    tdDays : Coeff := 1; 
    end; 

    RInteger := Trunc(input * Coeff); 
    DRInteger := RInteger div Range * Range 
    result := DRInteger/Coeff; 
    if (RInteger - DRInteger) >= (Range/2) then 
    result := result + Range/Coeff; 

end; 

Answer 3

嘗試使用DateUtils單位。
但是要在一分鐘，幾小時甚至幾秒鐘內舍入，只需解碼，然後將日期值編碼，並將毫秒，秒和分鐘設置爲零。舍入到幾分鐘或幾小時就意味着：解碼，將小時或分鐘舍入或舍入，然後重新編碼。
要對時間值進行編碼/解碼，請使用SysUtils的EncodeTime/DecodeTime。對日期使用EncodeDate/DecodeDate。應該可以用所有這些創建你自己的舍入函數。
此外，SysUtils函數具有常量，如MSecsPerDay，SecsPerDay，SecsPerMin，MinsPerHour和HoursPerDay。時間基本上是午夜過後的毫秒數。您可以使用MSecsPerDay進行壓縮壓縮（時間），這是精確的毫秒數。
不幸的是，由於時間值是​​浮動的，總會有小的舍入誤差的機會，因此你可能得不到預期的值...

Answer 4

哇！夥計們，你們怎麼把這麼簡單的事情搞得太複雜了......你們大多數人都沒有選擇輪到最接近的1/100秒，等等......

這一個更簡單，也可以輪到milisenconds部分：

function RoundToNearest(TheDateTime,TheRoundStep:TDateTime):TdateTime; 
    begin 
     if 0=TheRoundStep 
     then begin // If round step is zero there is no round at all 
        RoundToNearest:=TheDateTime; 
       end 
     else begin // Just round to nearest multiple of TheRoundStep 
        RoundToNearest:=Round(TheDateTime/TheRoundStep)*TheRoundStep; 
       end; 
    end; 

你可以只用這個共同的或不那麼常見的例子測試：

// Note: Scroll to bottom to see examples of round to 1/10 of a second, etc 

// Round to nearest multiple of one hour and a half (round to 90'=1h30') 
ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,156) 
             ,EncodeTime(1,30,0,0)) 
         ) 
      ); 

// Round to nearest multiple of one hour and a quarter (round to 75'=1h15') 
ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,156) 
             ,EncodeTime(1,15,0,0)) 
         ) 
      ); 

// Round to nearest multiple of 60 minutes (round to hours) 
ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,156) 
             ,EncodeTime(1,0,0,0)) 
         ) 
      ); 

// Round to nearest multiple of 60 seconds (round to minutes) 
ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,156) 
             ,EncodeTime(0,1,0,0)) 
         ) 
      ); 

// Round to nearest multiple of second (round to seconds) 
ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,156) 
             ,EncodeTime(0,0,1,0)) 
         ) 
      ); 

// Round to nearest multiple of 1/100 seconds 
ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,141) 
             ,EncodeTime(0,0,0,100)) 
         ) 
      ); 

// Round to nearest multiple of 1/100 seconds 
    ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,156) 
             ,EncodeTime(0,0,0,100)) 
         ) 
      ); 

// Round to nearest multiple of 1/10 seconds 
    ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,151) 
             ,EncodeTime(0,0,0,10)) 
         ) 
      ); 

// Round to nearest multiple of 1/10 seconds 
    ShowMessage(FormatDateTime('hh:nn:ss.zzz' 
          ,RoundToNearest(EncodeTime(15,31,37,156) 
             ,EncodeTime(0,0,0,10)) 
         ) 
      ); 

希望這有助於我這樣的人，那需要四捨五入到1/100，1/25 1/10秒。

Answer 5

如果你想綜述或ROUNDDOWN ...喜歡的Ceil和地板......

這裏有（不要忘記數學單元添加到您的使用條款）：

function RoundUpToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime; 
    begin 
     if 0=TheRoundStep 
     then begin // If round step is zero there is no round at all 
        RoundUpToNearest:=TheDateTime; 
       end 
     else begin // Just round up to nearest bigger or equal multiple of TheRoundStep 
        RoundUpToNearest:=Ceil(TheDateTime/TheRoundStep)*TheRoundStep; 
       end; 
    end; 

function RoundDownToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime; 
    begin 
     if 0=TheRoundStep 
     then begin // If round step is zero there is no round at all 
        RoundDownToNearest:=TheDateTime; 
       end 
     else begin // Just round down to nearest lower or equal multiple of TheRoundStep 
        RoundDownToNearest:=Floor(TheDateTime/TheRoundStep)*TheRoundStep; 
       end; 
    end; 

而且當然也可以用一個小的改變（使用浮點類型而不是TDateTime類型），如果也可以用來將Round，RoundUp和RoundDown的十進制/浮點值轉換爲十進制/浮點數。

在這裏，他們是：

function RoundUpToNearest(TheValue,TheRoundStep:Float):Float; 
    begin 
     if 0=TheRoundStep 
     then begin // If round step is zero there is no round at all 
        RoundUpToNearest:=TheValue; 
       end 
     else begin // Just round up to nearest bigger or equal multiple of TheRoundStep 
        RoundUpToNearest:=Ceil(TheValue/TheRoundStep)*TheRoundStep; 
       end; 
    end; 

function RoundToNearest(TheValue,TheRoundStep:Float):Float; 
    begin 
     if 0=TheRoundStep 
     then begin // If round step is zero there is no round at all 
        RoundToNearest:=TheValue; 
       end 
     else begin // Just round to nearest multiple of TheRoundStep 
        RoundToNearest:=Floor(TheValue/TheRoundStep)*TheRoundStep; 
       end; 
    end; 

function RoundDownToNearest(TheValue,TheRoundStep:Float):Float; 
    begin 
     if 0=TheRoundStep 
     then begin // If round step is zero there is no round at all 
        RoundDownToNearest:=TheDateTime; 
       end 
     else begin // Just round down to nearest lower or equal multiple of TheRoundStep 
        RoundDownToNearest:=Floor(TheValue/TheRoundStep)*TheRoundStep; 
       end; 
    end; 

如果你想同一個設備上使用兩種類型（TDateTime類型和Float）...在接口部分添加過載指令，例如：

function RoundUpToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;overload; 
function RoundToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;overload; 
function RoundDownToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;overload; 

function RoundUpToNearest(TheValue,TheRoundStep:Float):Float;overload; 
function RoundToNearest(TheValue,TheRoundStep:Float):Float;overload; 
function RoundDownToNearest(TheValue,TheRoundStep:Float):Float;overload; 

Answer 6

這是一個非常有用的代碼，我使用這個，因爲我發現日期時間傾向於「漂移」，如果你將它增加數小時或數分鐘多次，如果你正在嚴格的時間序列工作，這可能會搞砸了。例如00：00：00.000變成23：59：59.998 我實現了Gaben代碼的Sveins版本，但是我建議做一些修改：默認值對我來說不起作用，也是'（vTimeSec/SecsPerDay）'退出我認爲是一個錯誤，它不應該在那裏。我的代碼更正&評論，是：

Procedure TNumTool.RoundDateTimeToNearestInterval 
         (const ATime:TDateTime; AInterval:TDateTime{=5*60/SecsPerDay}; Var Result:TDateTime); 
    var           //Rounds to nearest 5-minute by default 
     vTimeSec,vIntSec,vRoundedSec : int64;  //NB datetime values are in days since 12/30/1899 as a double 
    begin 
     if AInterval = 0 then 
     AInterval := 5*60/SecsPerDay;     // no interval given - use default value of 5 minutes 
     vTimeSec := round(ATime * SecsPerDay);   // input time in seconds as integer 
     vIntSec := round(AInterval * SecsPerDay);  // interval time in seconds as integer 
     if vIntSec = 0 then 
     exit;           // interval is zero -cannot round the datetime; 
     vRoundedSec := round(vTimeSec/vIntSec) * vIntSec; // rounded time in seconds as integer 
     Result  := vRoundedSec/SecsPerDay;    // rounded time in days as tdatetime (double) 
    end;