CODEWITHSUNDEEP
c#random
DaveDave
DaveDave

Reputation: 303

Generate number 30% +- average number

I'm trying to create a random generator that takes a double value and outputs a new number that is either 30% over or under the input?

var result =  4 + random.NextDouble(); //output 4.2324355
var OverOrUnder = result + or - 20%

//Output to 1 decimal place
Console.WriteLine(OverOrUnder)

Also how can I print the result so that it's only printing to 1 decimal place

Upvotes: 0

Views: 108

Answers (4)

TheGeneral
TheGeneral

Reputation: 81543

Maybe

public static Random r = new Random();

public static double NextDouble(double value)
   => r.NextDouble() * (value * 1.3 - value * 0.7) + value * 0.7;

Or with an optional multiplier parameter and some simplifier math

public static double NextDouble(double value, double percent = 0.3)
   => r.NextDouble() * (2 * value *  percent) + value * (1 - percent);

Example

for (int i = 0; i < 10; i++)
   Console.WriteLine(NextDouble(100));

// Or for 1 decimal place

for (int i = 0; i < 10; i++)
   Console.WriteLine($"{NextDouble(100):N1}"))

Output

102.433669200369
83.64005585836249
116.86387416294957
88.28468969011898
77.75586905319051
83.67046313996914
115.69185544070407
104.68552079735582
122.76178736833938
82.53277266981675

...

78.9
108.2
72.4
91.4
87.7
116.1
96.4
124.8
120.5
101.0

Upvotes: 4

derpirscher
derpirscher

Reputation: 17400

If the 30% is fixed and just the sign is random you can try like this. random.NextInt(2) will generate either 0 or 1. And based on that it will multiply the input with either 0.7 (ie -30%) or 1.3 (ie +30%)

static void Main(string[] args)
{
    double input = 27.34;
    var random = new Random();
    var newvalue = input * (random.NextInt(2) == 0 ? 0.7 : 1.3);

    Console.WriteLine(newvalue.ToString("0.0"));
}

For formatting a double to your needs, see the docs of double.ToString() and either use a fixed format or a custom format for your needs.

Upvotes: 0

KhorAMus
KhorAMus

Reputation: 68

I hope this will work

    static void Main(string[] args)
    {
        double input = double.Parse(Console.ReadLine());
        var random = new Random();
        var overOrUnder = input + (random.NextDouble() - 0.5) * input * 0.3 * 2;

        Console.WriteLine($"{overOrUnder.ToString("0.0")}");
    }

Upvotes: 0

yaswanth Thamidallapati
yaswanth Thamidallapati

Reputation: 7

    Random random = new Random();
    var result = input + (random.NextDouble() - 0.5) * input * 0.3 * 2;
     //To print upto 1 decimal point
    Console.Write(string.Format("{0:0.0}",Math.Truncate(result*10)/10));

Upvotes: 0

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