Random.Sample Méthode
Définition
Important
Certaines informations portent sur la préversion du produit qui est susceptible d’être en grande partie modifiée avant sa publication. Microsoft exclut toute garantie, expresse ou implicite, concernant les informations fournies ici.
Retourne un nombre aléatoire à virgule flottante compris entre 0,0 et 1,0.
protected:
virtual double Sample();protected virtual double Sample ();abstract member Sample : unit -> double
override this.Sample : unit -> doubleProtected Overridable Function Sample () As DoubleRetours
Nombre à virgule flottante double précision supérieur ou égal à 0,0 et inférieur à 1,0.
Exemples
L’exemple suivant dérive une classe de Random et remplace la Sample méthode pour générer une distribution de nombres aléatoires. Cette distribution est différente de la distribution uniforme générée par la Sample méthode de la classe de base.
using namespace System;
// This derived class converts the uniformly distributed random
// numbers generated by base.Sample() to another distribution.
public ref class RandomProportional : Random
{
// The Sample method generates a distribution proportional to the value
// of the random numbers, in the range [0.0, 1.0].
protected:
virtual double Sample() override
{
return Math::Sqrt(Random::Sample());
}
public:
RandomProportional()
{}
virtual int Next() override
{
return (int) (Sample() * Int32::MaxValue);
}
};
int main(array<System::String ^> ^args)
{
const int rows = 4, cols = 6;
const int runCount = 1000000;
const int distGroupCount = 10;
const double intGroupSize =
((double) Int32::MaxValue + 1.0) / (double)distGroupCount;
RandomProportional ^randObj = gcnew RandomProportional();
array<int>^ intCounts = gcnew array<int>(distGroupCount);
array<int>^ realCounts = gcnew array<int>(distGroupCount);
Console::WriteLine(
"\nThe derived RandomProportional class overrides " +
"the Sample method to \ngenerate random numbers " +
"in the range [0.0, 1.0]. The distribution \nof " +
"the numbers is proportional to their numeric values. " +
"For example, \nnumbers are generated in the " +
"vicinity of 0.75 with three times the \n" +
"probability of those generated near 0.25.");
Console::WriteLine(
"\nRandom doubles generated with the NextDouble() " +
"method:\n");
// Generate and display [rows * cols] random doubles.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console::Write("{0,12:F8}", randObj->NextDouble());
Console::WriteLine();
}
Console::WriteLine(
"\nRandom integers generated with the Next() " +
"method:\n");
// Generate and display [rows * cols] random integers.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console::Write("{0,12}", randObj->Next());
Console::WriteLine();
}
Console::WriteLine(
"\nTo demonstrate the proportional distribution, " +
"{0:N0} random \nintegers and doubles are grouped " +
"into {1} equal value ranges. This \n" +
"is the count of values in each range:\n",
runCount, distGroupCount);
Console::WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "Integer Range",
"Count", "Double Range", "Count");
Console::WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "-------------",
"-----", "------------", "-----");
// Generate random integers and doubles, and then count
// them by group.
for (int i = 0; i < runCount; i++)
{
intCounts[ (int)((double)randObj->Next() /
intGroupSize) ]++;
realCounts[ (int)(randObj->NextDouble() *
(double)distGroupCount) ]++;
}
// Display the count of each group.
for (int i = 0; i < distGroupCount; i++)
Console::WriteLine(
"{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}",
(int)((double)i * intGroupSize),
(int)((double)(i + 1) * intGroupSize - 1.0),
intCounts[ i ],
((double)i) / (double)distGroupCount,
((double)(i + 1)) / (double)distGroupCount,
realCounts[ i ]);
return 0;
}
/*
This example of Random.Sample() displays output similar to the following:
The derived RandomProportional class overrides the Sample method to
generate random numbers in the range [0.0, 1.0). The distribution
of the numbers is proportional to the number values. For example,
numbers are generated in the vicinity of 0.75 with three times the
probability of those generated near 0.25.
Random doubles generated with the NextDouble() method:
0.59455719 0.17589882 0.83134398 0.35795862 0.91467727 0.54022658
0.93716947 0.54817519 0.94685080 0.93705478 0.18582318 0.71272428
0.77708682 0.95386216 0.70412393 0.86099417 0.08275804 0.79108316
0.71019941 0.84205103 0.41685082 0.58186880 0.89492302 0.73067715
Random integers generated with the Next() method:
1570755704 1279192549 1747627711 1705700211 1372759203 1849655615
2046235980 1210843924 1554274149 1307936697 1480207570 1057595022
337854215 844109928 2028310798 1386669369 2073517658 1291729809
1537248240 1454198019 1934863511 1640004334 2032620207 534654791
To demonstrate the proportional distribution, 1,000,000 random
integers and doubles are grouped into 10 equal value ranges. This
is the count of values in each range:
Integer Range Count Double Range Count
------------- ----- ------------ -----
0- 214748363 10,079 0.00000-0.10000 10,148
214748364- 429496728 29,835 0.10000-0.20000 29,849
429496729- 644245093 49,753 0.20000-0.30000 49,948
644245094- 858993458 70,325 0.30000-0.40000 69,656
858993459-1073741823 89,906 0.40000-0.50000 90,337
1073741824-1288490187 109,868 0.50000-0.60000 110,225
1288490188-1503238552 130,388 0.60000-0.70000 129,986
1503238553-1717986917 149,231 0.70000-0.80000 150,428
1717986918-1932735282 170,234 0.80000-0.90000 169,610
1932735283-2147483647 190,381 0.90000-1.00000 189,813
*/
using System;
// This derived class converts the uniformly distributed random
// numbers generated by base.Sample() to another distribution.
public class RandomProportional : Random
{
// The Sample method generates a distribution proportional to the value
// of the random numbers, in the range [0.0, 1.0].
protected override double Sample()
{
return Math.Sqrt(base.Sample());
}
public override int Next()
{
return (int) (Sample() * int.MaxValue);
}
}
public class RandomSampleDemo
{
static void Main()
{
const int rows = 4, cols = 6;
const int runCount = 1000000;
const int distGroupCount = 10;
const double intGroupSize =
((double)int.MaxValue + 1.0) / (double)distGroupCount;
RandomProportional randObj = new RandomProportional();
int[ ] intCounts = new int[ distGroupCount ];
int[ ] realCounts = new int[ distGroupCount ];
Console.WriteLine(
"\nThe derived RandomProportional class overrides " +
"the Sample method to \ngenerate random numbers " +
"in the range [0.0, 1.0]. The distribution \nof " +
"the numbers is proportional to their numeric values. " +
"For example, \nnumbers are generated in the " +
"vicinity of 0.75 with three times the \n" +
"probability of those generated near 0.25.");
Console.WriteLine(
"\nRandom doubles generated with the NextDouble() " +
"method:\n");
// Generate and display [rows * cols] random doubles.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console.Write("{0,12:F8}", randObj.NextDouble());
Console.WriteLine();
}
Console.WriteLine(
"\nRandom integers generated with the Next() " +
"method:\n");
// Generate and display [rows * cols] random integers.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console.Write("{0,12}", randObj.Next());
Console.WriteLine();
}
Console.WriteLine(
"\nTo demonstrate the proportional distribution, " +
"{0:N0} random \nintegers and doubles are grouped " +
"into {1} equal value ranges. This \n" +
"is the count of values in each range:\n",
runCount, distGroupCount);
Console.WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "Integer Range",
"Count", "Double Range", "Count");
Console.WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "-------------",
"-----", "------------", "-----");
// Generate random integers and doubles, and then count
// them by group.
for (int i = 0; i < runCount; i++)
{
intCounts[ (int)((double)randObj.Next() /
intGroupSize) ]++;
realCounts[ (int)(randObj.NextDouble() *
(double)distGroupCount) ]++;
}
// Display the count of each group.
for (int i = 0; i < distGroupCount; i++)
Console.WriteLine(
"{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}",
(int)((double)i * intGroupSize),
(int)((double)(i + 1) * intGroupSize - 1.0),
intCounts[ i ],
((double)i) / (double)distGroupCount,
((double)(i + 1)) / (double)distGroupCount,
realCounts[ i ]);
}
}
/*
This example of Random.Sample() displays output similar to the following:
The derived RandomProportional class overrides the Sample method to
generate random numbers in the range [0.0, 1.0). The distribution
of the numbers is proportional to the number values. For example,
numbers are generated in the vicinity of 0.75 with three times the
probability of those generated near 0.25.
Random doubles generated with the NextDouble() method:
0.59455719 0.17589882 0.83134398 0.35795862 0.91467727 0.54022658
0.93716947 0.54817519 0.94685080 0.93705478 0.18582318 0.71272428
0.77708682 0.95386216 0.70412393 0.86099417 0.08275804 0.79108316
0.71019941 0.84205103 0.41685082 0.58186880 0.89492302 0.73067715
Random integers generated with the Next() method:
1570755704 1279192549 1747627711 1705700211 1372759203 1849655615
2046235980 1210843924 1554274149 1307936697 1480207570 1057595022
337854215 844109928 2028310798 1386669369 2073517658 1291729809
1537248240 1454198019 1934863511 1640004334 2032620207 534654791
To demonstrate the proportional distribution, 1,000,000 random
integers and doubles are grouped into 10 equal value ranges. This
is the count of values in each range:
Integer Range Count Double Range Count
------------- ----- ------------ -----
0- 214748363 10,079 0.00000-0.10000 10,148
214748364- 429496728 29,835 0.10000-0.20000 29,849
429496729- 644245093 49,753 0.20000-0.30000 49,948
644245094- 858993458 70,325 0.30000-0.40000 69,656
858993459-1073741823 89,906 0.40000-0.50000 90,337
1073741824-1288490187 109,868 0.50000-0.60000 110,225
1288490188-1503238552 130,388 0.60000-0.70000 129,986
1503238553-1717986917 149,231 0.70000-0.80000 150,428
1717986918-1932735282 170,234 0.80000-0.90000 169,610
1932735283-2147483647 190,381 0.90000-1.00000 189,813
*/
open System
// This derived class converts the uniformly distributed random
// numbers generated by base.Sample() to another distribution.
type RandomProportional() =
inherit Random()
// The Sample method generates a distribution proportional to the value
// of the random numbers, in the range [0.0, 1.0].
override _.Sample() =
sqrt (base.Sample())
override this.Next() =
this.Sample() * float Int32.MaxValue
|> int
let [<Literal>] rows = 4
let [<Literal>] cols = 6
let [<Literal>] runCount = 1000000
let [<Literal>] distGroupCount = 10
let intGroupSize =
(float Int32.MaxValue + 1.0) / float distGroupCount
let randObj = RandomProportional()
printfn """
The derived RandomProportional class overrides the Sample method to
generate random numbers in the range [0.0, 1.0]. The distribution
of the numbers is proportional to their numeric values. For example,
numbers are generated in the vicinity of 0.75 with three times the
probability of those generated near 0.25."""
printfn "\nRandom doubles generated with the NextDouble() method:\n"
// Generate and display [rows * cols] random doubles.
for _ = 1 to rows do
for _ = 1 to cols do
printf $"{randObj.NextDouble(),12:F8}"
printfn ""
printfn "\nRandom integers generated with the Next() method:\n"
// Generate and display [rows * cols] random integers.
for _ = 1 to rows do
for _ = 1 to cols do
printf $"{randObj.Next(),12}"
printfn ""
printfn $"""
To demonstrate the proportional distribution, {runCount:N0} random
integers and doubles are grouped into {distGroupCount} equal value ranges. This
is the count of values in each range:
"""
printfn $"""{"Integer Range",21}{"Count",10}{"Double Range",20}{"Count",10}"""
printfn $"""{"-------------",21}{"-----",10}{"------------",20}{"-----",10}"""
// Generate random integers and doubles, and then count them by group.
let intCounts =
Array.init runCount (fun _ ->
(randObj.Next() |> float) / float intGroupSize
|> int )
|> Array.countBy id
|> Array.map snd
let realCounts =
Array.init runCount (fun _ ->
randObj.NextDouble() * float distGroupCount
|> int )
|> Array.countBy id
|> Array.map snd
// Display the count of each group.
for i = 0 to distGroupCount - 1 do
Console.WriteLine(
"{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}",
int(float i * intGroupSize),
int(float (i + 1) * intGroupSize - 1.0),
intCounts.[i],
(float i) / float distGroupCount,
float (i + 1) / float distGroupCount,
realCounts.[i])
(*
This example of Random.Sample() displays output similar to the following:
The derived RandomProportional class overrides the Sample method to
generate random numbers in the range [0.0, 1.0). The distribution
of the numbers is proportional to the number values. For example,
numbers are generated in the vicinity of 0.75 with three times the
probability of those generated near 0.25.
Random doubles generated with the NextDouble() method:
0.59455719 0.17589882 0.83134398 0.35795862 0.91467727 0.54022658
0.93716947 0.54817519 0.94685080 0.93705478 0.18582318 0.71272428
0.77708682 0.95386216 0.70412393 0.86099417 0.08275804 0.79108316
0.71019941 0.84205103 0.41685082 0.58186880 0.89492302 0.73067715
Random integers generated with the Next() method:
1570755704 1279192549 1747627711 1705700211 1372759203 1849655615
2046235980 1210843924 1554274149 1307936697 1480207570 1057595022
337854215 844109928 2028310798 1386669369 2073517658 1291729809
1537248240 1454198019 1934863511 1640004334 2032620207 534654791
To demonstrate the proportional distribution, 1,000,000 random
integers and doubles are grouped into 10 equal value ranges. This
is the count of values in each range:
Integer Range Count Double Range Count
------------- ----- ------------ -----
0- 214748363 10,079 0.00000-0.10000 10,148
214748364- 429496728 29,835 0.10000-0.20000 29,849
429496729- 644245093 49,753 0.20000-0.30000 49,948
644245094- 858993458 70,325 0.30000-0.40000 69,656
858993459-1073741823 89,906 0.40000-0.50000 90,337
1073741824-1288490187 109,868 0.50000-0.60000 110,225
1288490188-1503238552 130,388 0.60000-0.70000 129,986
1503238553-1717986917 149,231 0.70000-0.80000 150,428
1717986918-1932735282 170,234 0.80000-0.90000 169,610
1932735283-2147483647 190,381 0.90000-1.00000 189,813
*)
' This derived class converts the uniformly distributed random
' numbers generated by base.Sample() to another distribution.
Public Class RandomProportional
Inherits Random
' The Sample method generates a distribution proportional to the value
' of the random numbers, in the range [0.0, 1.0].
Protected Overrides Function Sample() As Double
Return Math.Sqrt(MyBase.Sample())
End Function
Public Overrides Function [Next]() As Integer
Return Sample() * Integer.MaxValue
End Function
End Class
Module RandomSampleDemo
Sub Main()
Const rows As Integer = 4, cols As Integer = 6
Const runCount As Integer = 1000000
Const distGroupCount As Integer = 10
Const intGroupSize As Double = _
(CDbl(Integer.MaxValue) + 1.0) / _
CDbl(distGroupCount)
Dim randObj As New RandomProportional()
Dim intCounts(distGroupCount) As Integer
Dim realCounts(distGroupCount) As Integer
Dim i As Integer, j As Integer
Console.WriteLine(vbCrLf & _
"The derived RandomProportional class overrides " & _
"the Sample method to " & vbCrLf & _
"generate random numbers in the range " & _
"[0.0, 1.0]. The distribution " & vbCrLf & _
"of the numbers is proportional to their numeric " & _
"values. For example, " & vbCrLf & _
"numbers are generated in the vicinity of 0.75 " & _
"with three times " & vbCrLf & "the " & _
"probability of those generated near 0.25.")
Console.WriteLine(vbCrLf & _
"Random doubles generated with the NextDouble() " & _
"method:" & vbCrLf)
' Generate and display [rows * cols] random doubles.
For i = 0 To rows - 1
For j = 0 To cols - 1
Console.Write("{0,12:F8}", randObj.NextDouble())
Next j
Console.WriteLine()
Next i
Console.WriteLine(vbCrLf & _
"Random integers generated with the Next() " & _
"method:" & vbCrLf)
' Generate and display [rows * cols] random integers.
For i = 0 To rows - 1
For j = 0 To cols - 1
Console.Write("{0,12}", randObj.Next())
Next j
Console.WriteLine()
Next i
Console.WriteLine(vbCrLf & _
"To demonstrate the proportional distribution, " & _
"{0:N0} random " & vbCrLf & _
"integers and doubles are grouped into {1} " & _
"equal value ranges. This " & vbCrLf & _
"is the count of values in each range:" & vbCrLf, _
runCount, distGroupCount)
Console.WriteLine("{0,21}{1,10}{2,20}{3,10}", _
"Integer Range", "Count", "Double Range", "Count")
Console.WriteLine("{0,21}{1,10}{2,20}{3,10}", _
"-------------", "-----", "------------", "-----")
' Generate random integers and doubles, and then count
' them by group.
For i = 0 To runCount - 1
intCounts(Fix(CDbl(randObj.Next()) / _
intGroupSize)) += 1
realCounts(Fix(randObj.NextDouble() * _
CDbl(distGroupCount))) += 1
Next i
' Display the count of each group.
For i = 0 To distGroupCount - 1
Console.WriteLine( _
"{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}", _
Fix(CDbl(i) * intGroupSize), _
Fix(CDbl(i + 1) * intGroupSize - 1.0), _
intCounts(i), _
CDbl(i) / CDbl(distGroupCount), _
CDbl(i + 1) / CDbl(distGroupCount), _
realCounts(i))
Next i
End Sub
End Module
' This example of Random.Sample() generates output similar to the following:
'
' The derived RandomProportional class overrides the Sample method to
' generate random numbers in the range [0.0, 1.0]. The distribution
' of the numbers is proportional to their numeric values. For example,
' numbers are generated in the vicinity of 0.75 with three times
' the probability of those generated near 0.25.
'
' Random doubles generated with the NextDouble() method:
'
' 0.28377004 0.75920598 0.33430371 0.66720626 0.97080243 0.27353772
' 0.17787962 0.54618410 0.08145080 0.56286100 0.99002910 0.64898614
' 0.27673277 0.99455281 0.93778966 0.76162002 0.70533771 0.44375798
' 0.55939883 0.87383136 0.66465779 0.77392566 0.42393411 0.82409159
'
' Random integers generated with the Next() method:
'
' 1364479914 1230312341 1657373812 1526222928 988564704 700078020
' 1801013705 1541517421 1146312560 338318389 1558995993 2027260859
' 884520932 1320070465 570200106 1027684711 943035246 2088689333
' 630809089 1705728475 2140787648 2097858166 1863010875 1386804198
'
' To demonstrate the proportional distribution, 1,000,000 random
' integers and doubles are grouped into 10 equal value ranges. This
' is the count of values in each range:
'
' Integer Range Count Double Range Count
' ------------- ----- ------------ -----
' 0- 214748363 9,892 0.00000-0.10000 9,928
' 214748364- 429496728 30,341 0.10000-0.20000 30,101
' 429496729- 644245093 49,958 0.20000-0.30000 49,964
' 644245094- 858993458 70,099 0.30000-0.40000 70,213
' 858993459-1073741823 90,801 0.40000-0.50000 89,553
' 1073741824-1288490187 109,699 0.50000-0.60000 109,427
' 1288490188-1503238552 129,438 0.60000-0.70000 130,339
' 1503238553-1717986917 149,886 0.70000-0.80000 150,000
' 1717986918-1932735282 170,338 0.80000-0.90000 170,128
' 1932735283-2147483647 189,548 0.90000-1.00000 190,347
Remarques
Pour produire une distribution aléatoire différente ou un autre principe de générateur de nombres aléatoires, dérivez une classe de la Random classe et remplacez la Sample méthode .
Important
La Sample méthode est protected, ce qui signifie qu’elle est accessible uniquement dans la Random classe et ses classes dérivées. Pour générer un nombre aléatoire compris entre 0 et 1 à partir d’un Random instance, appelez la NextDouble méthode .
Notes pour les héritiers
À compter de la version 2.0 du .NET Framework, si vous dérivez une classe de Random et remplacez la Sample() méthode, la distribution fournie par l’implémentation de classe dérivée de la Sample() méthode n’est pas utilisée dans les appels à l’implémentation de classe de base des méthodes suivantes :
Méthode NextBytes(Byte[])
Méthode Next()
La Next(Int32, Int32) méthode, si (
maxValue-minValue) est supérieur à Int32.MaxValue.
Au lieu de cela, la distribution uniforme fournie par la classe de base Random est utilisée. Ce comportement améliore les performances globales de la Random classe . Pour modifier ce comportement afin d’appeler l’implémentation de la Sample() méthode dans la classe dérivée, vous devez également remplacer le comportement de ces trois membres. Cet exemple en fournit une illustration.
S’applique à
Voir aussi
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