Random.NextDouble メソッド
定義
重要
一部の情報は、リリース前に大きく変更される可能性があるプレリリースされた製品に関するものです。 Microsoft は、ここに記載されている情報について、明示または黙示を問わず、一切保証しません。
0.0 以上 1.0 未満のランダムな浮動小数点数を返します。
public:
virtual double NextDouble();public virtual double NextDouble ();abstract member NextDouble : unit -> double
override this.NextDouble : unit -> doublePublic Overridable Function NextDouble () As Double戻り値
0.0 以上 1.0 未満の倍精度浮動小数点数。
例
次の例では、このメソッドを NextDouble 使用してランダム倍精度浮動小数点のシーケンスを生成します。
// Example of the Random class constructors and Random::NextDouble()
// method.
using namespace System;
using namespace System::Threading;
// Generate random numbers from the specified Random object.
void RunIntNDoubleRandoms(Random^ randObj)
{
// Generate the first six random integers.
for (int j = 0; j < 6; j++)
Console::Write(" {0,10} ", randObj->Next());
Console::WriteLine();
// Generate the first six random doubles.
for (int j = 0; j < 6; j++)
Console::Write(" {0:F8} ", randObj->NextDouble());
Console::WriteLine();
}
// Create a Random object with the specified seed.
void FixedSeedRandoms(int seed)
{
Console::WriteLine("\nRandom numbers from a Random object with seed = {0}:", seed);
Random^ fixRand = gcnew Random(seed);
RunIntNDoubleRandoms(fixRand);
}
// Create a random object with a timer-generated seed.
void AutoSeedRandoms()
{
// Wait to allow the timer to advance.
Thread::Sleep(1);
Console::WriteLine("\nRandom numbers from a Random object "
"with an auto-generated seed:");
Random^ autoRand = gcnew Random;
RunIntNDoubleRandoms(autoRand);
}
int main()
{
Console::WriteLine("This example of the Random class constructors and Random"
"::NextDouble() \ngenerates the following output.\n");
Console::WriteLine("Create Random objects, and then generate and "
"display six integers and \nsix doubles from each.");
FixedSeedRandoms(123);
FixedSeedRandoms(123);
FixedSeedRandoms(456);
FixedSeedRandoms(456);
AutoSeedRandoms();
AutoSeedRandoms();
AutoSeedRandoms();
}
/*
This example of the Random class constructors and Random::NextDouble()
generates an output similar to the following:
Create Random objects, and then generate and display six integers and
six doubles from each.
Random numbers from a Random object with seed = 123:
2114319875 1949518561 1596751841 1742987178 1586516133 103755708
0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
Random numbers from a Random object with seed = 123:
2114319875 1949518561 1596751841 1742987178 1586516133 103755708
0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
Random numbers from a Random object with seed = 456:
2044805024 1323311594 1087799997 1907260840 179380355 120870348
0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
Random numbers from a Random object with seed = 456:
2044805024 1323311594 1087799997 1907260840 179380355 120870348
0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
Random numbers from a Random object with an auto-generated seed:
1624372556 1894939458 302472229 588108304 23919954 1085111949
0.14595512 0.30162298 0.92267372 0.55707657 0.25430079 0.74143239
Random numbers from a Random object with an auto-generated seed:
2105952511 1753605347 280739490 876793040 1129567796 524571616
0.62652210 0.31846701 0.15984073 0.24458755 0.62160607 0.54857684
Random numbers from a Random object with an auto-generated seed:
440048819 1612271236 259006751 1165477776 87731991 2111514930
0.10708907 0.33531104 0.39700773 0.93209853 0.98891135 0.35572129
*/
// Example of the Random class constructors and Random.NextDouble()
// method.
using System;
using System.Threading;
public class RandomObjectDemo
{
// Generate random numbers from the specified Random object.
static void RunIntNDoubleRandoms(Random randObj)
{
// Generate the first six random integers.
for(int j = 0; j < 6; j++)
Console.Write(" {0,10} ", randObj.Next());
Console.WriteLine();
// Generate the first six random doubles.
for(int j = 0; j < 6; j++)
Console.Write(" {0:F8} ", randObj.NextDouble());
Console.WriteLine();
}
// Create a Random object with the specified seed.
static void FixedSeedRandoms(int seed)
{
Console.WriteLine(
"\nRandom numbers from a Random object with " +
"seed = {0}:", seed);
Random fixRand = new Random(seed);
RunIntNDoubleRandoms(fixRand);
}
// Create a random object with a timer-generated seed.
static void AutoSeedRandoms()
{
// Wait to allow the timer to advance.
Thread.Sleep(1);
Console.WriteLine(
"\nRandom numbers from a Random object " +
"with an auto-generated seed:");
Random autoRand = new Random();
RunIntNDoubleRandoms(autoRand);
}
static void Main()
{
Console.WriteLine(
"This example of the Random class constructors and " +
"Random.NextDouble() \n" +
"generates the following output.\n");
Console.WriteLine(
"Create Random objects, and then generate and " +
"display six integers and \nsix doubles from each.");
FixedSeedRandoms(123);
FixedSeedRandoms(123);
FixedSeedRandoms(456);
FixedSeedRandoms(456);
AutoSeedRandoms();
AutoSeedRandoms();
AutoSeedRandoms();
}
}
/*
This example of the Random class constructors and Random.NextDouble()
generates an output similar to the following:
Create Random objects, and then generate and display six integers and
six doubles from each.
Random numbers from a Random object with seed = 123:
2114319875 1949518561 1596751841 1742987178 1586516133 103755708
0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
Random numbers from a Random object with seed = 123:
2114319875 1949518561 1596751841 1742987178 1586516133 103755708
0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
Random numbers from a Random object with seed = 456:
2044805024 1323311594 1087799997 1907260840 179380355 120870348
0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
Random numbers from a Random object with seed = 456:
2044805024 1323311594 1087799997 1907260840 179380355 120870348
0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
Random numbers from a Random object with an auto-generated seed:
380213349 127379247 1969091178 1983029819 1963098450 1648433124
0.08824121 0.41249688 0.36445811 0.05637512 0.62702451 0.49595560
Random numbers from a Random object with an auto-generated seed:
861793304 2133528783 1947358439 124230908 921262645 1087892791
0.56880819 0.42934091 0.60162512 0.74388610 0.99432979 0.30310005
Random numbers from a Random object with an auto-generated seed:
1343373259 1992194672 1925625700 412915644 2026910487 527352458
0.04937517 0.44618494 0.83879212 0.43139707 0.36163507 0.11024451
*/
// Example of the Random class constructors and Random.NextDouble()
// method.
open System
open System.Threading
// Generate random numbers from the specified Random object.
let runIntNDoubleRandoms (randObj: Random) =
// Generate the first six random integers.
for _ = 1 to 6 do
printf $" {randObj.Next(),10} "
printfn ""
// Generate the first six random doubles.
for _ = 1 to 6 do
printf $" {randObj.NextDouble():F8} "
printfn ""
let fixedSeedRandoms seed =
printfn $"\nRandom numbers from a Random object with seed = %i{seed}:"
let fixRand = Random seed
runIntNDoubleRandoms fixRand
let autoSeedRandoms () =
// Wait to allow the timer to advance.
Thread.Sleep 1
printfn "\nRandom numbers from a Random object with an auto-generated seed: "
let autoRand = Random ()
runIntNDoubleRandoms autoRand
printfn
"""This example of the Random class constructors and Random.NextDouble()
generates the following output.
Create Random objects, and then generate and display six integers and
six doubles from each."""
fixedSeedRandoms 123
fixedSeedRandoms 123
fixedSeedRandoms 456
fixedSeedRandoms 456
autoSeedRandoms ()
autoSeedRandoms ()
autoSeedRandoms ()
(*
This example of the Random class constructors and Random.NextDouble()
generates an output similar to the following:
Create Random objects, and then generate and display six integers and
six doubles from each.
Random numbers from a Random object with seed = 123:
2114319875 1949518561 1596751841 1742987178 1586516133 103755708
0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
Random numbers from a Random object with seed = 123:
2114319875 1949518561 1596751841 1742987178 1586516133 103755708
0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
Random numbers from a Random object with seed = 456:
2044805024 1323311594 1087799997 1907260840 179380355 120870348
0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
Random numbers from a Random object with seed = 456:
2044805024 1323311594 1087799997 1907260840 179380355 120870348
0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
Random numbers from a Random object with an auto-generated seed:
380213349 127379247 1969091178 1983029819 1963098450 1648433124
0.08824121 0.41249688 0.36445811 0.05637512 0.62702451 0.49595560
Random numbers from a Random object with an auto-generated seed:
861793304 2133528783 1947358439 124230908 921262645 1087892791
0.56880819 0.42934091 0.60162512 0.74388610 0.99432979 0.30310005
Random numbers from a Random object with an auto-generated seed:
1343373259 1992194672 1925625700 412915644 2026910487 527352458
0.04937517 0.44618494 0.83879212 0.43139707 0.36163507 0.11024451
*)
' Example of the Random class constructors and Random.NextDouble()
' method.
Imports System.Threading
Module RandomObjectDemo
' Generate random numbers from the specified Random object.
Sub RunIntNDoubleRandoms(randObj As Random)
' Generate the first six random integers.
Dim j As Integer
For j = 0 To 5
Console.Write(" {0,10} ", randObj.Next())
Next j
Console.WriteLine()
' Generate the first six random doubles.
For j = 0 To 5
Console.Write(" {0:F8} ", randObj.NextDouble())
Next j
Console.WriteLine()
End Sub
' Create a Random object with the specified seed.
Sub FixedSeedRandoms(seed As Integer)
Console.WriteLine(vbCrLf & _
"Random numbers from a Random object with " & _
"seed = {0}:", seed)
Dim fixRand As New Random(seed)
RunIntNDoubleRandoms(fixRand)
End Sub
' Create a random object with a timer-generated seed.
Sub AutoSeedRandoms()
' Wait to allow the timer to advance.
Thread.Sleep(1)
Console.WriteLine(vbCrLf & _
"Random numbers from a Random object " & _
"with an auto-generated seed:")
Dim autoRand As New Random()
RunIntNDoubleRandoms(autoRand)
End Sub
Sub Main()
Console.WriteLine(_
"This example of the Random class constructors " & _
"and Random.NextDouble() " & vbCrLf & _
"generates the following output." & vbCrLf)
Console.WriteLine("Create Random " & _
"objects, and then generate and display six " & _
"integers and " & vbCrLf & "six doubles from each.")
FixedSeedRandoms(123)
FixedSeedRandoms(123)
FixedSeedRandoms(456)
FixedSeedRandoms(456)
AutoSeedRandoms()
AutoSeedRandoms()
AutoSeedRandoms()
End Sub
End Module
' This example of the Random class constructors and Random.NextDouble()
' generates an output similar to the following:
'
' Create Random objects, and then generate and display six integers and
' six doubles from each.
'
' Random numbers from a Random object with seed = 123:
' 2114319875 1949518561 1596751841 1742987178 1586516133 103755708
' 0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
'
' Random numbers from a Random object with seed = 123:
' 2114319875 1949518561 1596751841 1742987178 1586516133 103755708
' 0.01700087 0.14935942 0.19470390 0.63008947 0.90976122 0.49519146
'
' Random numbers from a Random object with seed = 456:
' 2044805024 1323311594 1087799997 1907260840 179380355 120870348
' 0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
'
' Random numbers from a Random object with seed = 456:
' 2044805024 1323311594 1087799997 1907260840 179380355 120870348
' 0.21988117 0.21026556 0.39236514 0.42420498 0.24102703 0.47310170
'
' Random numbers from a Random object with an auto-generated seed:
' 1920831619 1346865774 2006582766 1968819760 332463652 110770792
' 0.71326689 0.50383335 0.50446082 0.66312569 0.94517193 0.58059287
'
' Random numbers from a Random object with an auto-generated seed:
' 254927927 1205531663 1984850027 110020849 1438111494 1697714106
' 0.19383387 0.52067738 0.74162783 0.35063667 0.31247720 0.38773733
'
' Random numbers from a Random object with an auto-generated seed:
' 736507882 1064197552 1963117288 398705585 396275689 1137173773
' 0.67440084 0.53752140 0.97879483 0.03814764 0.67978248 0.19488178
次の例では、メソッドを NextDouble 呼び出して 100 個の乱数を生成し、その頻度分布を表示します。
int[] frequency = new int[10];
double number;
Random rnd = new Random();
for (int ctr = 0; ctr <= 99; ctr++) {
number = rnd.NextDouble();
frequency[(int) Math.Floor(number*10)] ++;
}
Console.WriteLine("Distribution of Random Numbers:");
for (int ctr = frequency.GetLowerBound(0); ctr <= frequency.GetUpperBound(0); ctr++)
Console.WriteLine("0.{0}0-0.{0}9 {1}", ctr, frequency[ctr]);
// The following example displays output similar to the following:
// Distribution of Random Numbers:
// 0.00-0.09 16
// 0.10-0.19 8
// 0.20-0.29 8
// 0.30-0.39 11
// 0.40-0.49 9
// 0.50-0.59 6
// 0.60-0.69 13
// 0.70-0.79 6
// 0.80-0.89 9
// 0.90-0.99 14
let rnd = Random()
let frequency =
Array.init 100 (fun _ ->
let number = rnd.NextDouble()
floor (number * 10.0) |> int )
|> Array.countBy id
|> Array.map snd
printfn "Distribution of Random Numbers:"
for i = frequency.GetLowerBound 0 to frequency.GetUpperBound 0 do
printfn $"0.{i}0-0.{i}9 {frequency.[i]}"
// The following example displays output similar to the following:
// Distribution of Random Numbers:
// 0.00-0.09 16
// 0.10-0.19 8
// 0.20-0.29 8
// 0.30-0.39 11
// 0.40-0.49 9
// 0.50-0.59 6
// 0.60-0.69 13
// 0.70-0.79 6
// 0.80-0.89 9
// 0.90-0.99 14
Module Example
Public Sub Main()
Dim frequency(9) As Integer
Dim number As Double
Dim rnd As New Random()
For ctr As Integer = 0 To 99
number = rnd.NextDouble()
frequency(CInt(Math.Floor(number*10))) += 1
Next
Console.WriteLine("Distribution of Random Numbers:")
For ctr As Integer = frequency.GetLowerBound(0) To frequency.GetUpperBound(0)
Console.WriteLine("0.{0}0-0.{0}9 {1}", ctr, frequency(ctr))
Next
End Sub
End Module
' The following example displays output similar to the following:
' Distribution of Random Numbers:
' 0.00-0.09 16
' 0.10-0.19 8
' 0.20-0.29 8
' 0.30-0.39 11
' 0.40-0.49 9
' 0.50-0.59 6
' 0.60-0.69 13
' 0.70-0.79 6
' 0.80-0.89 9
' 0.90-0.99 14
注釈
このメソッドによって返される乱数の実際の上限は 0.99999999999999978 です。
0.0 および 1.0 以外の範囲内のランダムな浮動小数点値を取得するには、クラス トピックの「指定した範囲内の浮動小数点値を取得する」セクションを Random 参照してください。
このメソッドは、保護されたメソッドのパブリック バージョンです Sample。