random between a range

[RTollison 0]

currently use a loop and random to get a value between a range.

first on was simple enough

value1 := random (250) + 1 (value from 1 thru 250)

second halfway simple

value2 := random(500) + 1; set initial random value

while value2 < 251 do

  value2 := random(500) + 1;

value3 := random(750) + 1;

while value3 < 501 do 

  value3 := random(750) + 1;

value4 := random(1000) + 1;

while value4 < 751 do

   value4 := random(1000) + 1;

 

sometimes it is pretty quick, other times is seems to hang for a bit. < 10 seconds

so that got me to thinking, is there a better way to random values bewteen a range?

[corneliusdavid 142]

So you want 4 random values, one each in the ranges 1-250, 251-500, 501-750, and 751-1000, right:

Try this:

value1 := random(250) + 1;
value2 := random(250) + 250;
value3 := random(250) + 500;
value4 := random(250) + 750;

Each random number is restricted to a 250 range but adding a number to it puts it into different range brackets.

[Anders Melander 1639]

Your code makes no sense.

 

Instead of:

value2 := random(500) + 1;
while value2 < 251 do
  value2 := random(500) + 1;

why don't you just:

// Values from 251 to 500
value2 := 251 + random(250);

 

[RTollison 0]

thank you all. yeah i didnt think this one thru very well did I. used to our cobol random command and didn't even go to the point of adding a larger value than 1. 

sorry for such a stupid question...

[David Heffernan 2300]

31 minutes ago, corneliusdavid said:

So you want 4 random values, one each in the ranges 1-250, 251-500, 501-750, and 751-1000, right:

Try this:

value1 := random(250) + 1;
value2 := random(250) + 250;
value3 := random(250) + 500;
value4 := random(250) + 750;

Each random number is restricted to a 250 range but adding a number to it puts it into different range brackets.

value2, value3, value 4 all have an off by one error. 

[corneliusdavid 142]

Just now, David Heffernan said:

value2, value3, value 4 all have an off by one error. 

DOH! Corrected:

value1 := random(250) + 1;
value2 := random(250) + 251;
value3 := random(250) + 501;
value4 := random(250) + 751;

 

[RTollison 0]

got that implemented, thanks again.

now he asked be something else and if i am  correct, he is asking for overlapping numbers with without duplicating them. i can deal with any duplicates with a while statement but here is basically what is asking for. 

value1 = 1-300

value2 = 100-550

value3 = 250-750

value4 = 500-1000

not sure what he is looking for but he wanted me to let him enter the ranges instead of the hardcoded ranges (which is what he said he wanted but now wants to expand upon for his own purposes).

i asked about any of the overlaps if he wanted to force then higher and he said that the overlapping is fine.

so if we retrieve values like

value1=225

value2=200

value3=299

value4=500 

That would be ok. told him that I had no idea how this is helping. why not throw darts at a board.  but he said now he could put his dart board away.

 

[Remy Lebeau 1260]

2 hours ago, RTollison said:

now he asked be something else and if i am  correct, he is asking for overlapping numbers with without duplicating them.

One option would be to create 4 lists and fill them with the possible numbers, and then generate a random index for each list, where you remove each found number from subsequent lists before generating indexes for them. For example:

var
  values1, values2, values3, values4: TList<Integer>;
  value1, value2, value3, value4, index: Integer;

  procedure populate(list: TList<Integer>; startValue, endValue: Integer);
  var
    value: Integer;
  begin
    list.Capacity := endValue - startValue + 1;
    for value := startValue to endValue do
      list.Add(value);
  end;

  procedure checkAndRemove(list: TList<Integer>; startValue, endValue, valueToRemove: Integer);
  begin
    if (valueToRemove >= startValue) and (valueToRemove <= endValue) then
      list.Remove(valueToRemove);
  end;

begin
  values1 := TList<Integer>.Create;
  values2 := TList<Integer>.Create;
  values3 := TList<Integer>.Create;
  values4 := TList<Integer>.Create;

  populate(values1, 1, 300);
  populate(values2, 100, 550);
  populate(values3, 250, 750);
  populate(values4, 500, 1000);

  index := random(values1.Count);
  value1 := values1[index];

  checkAndRemove(values2, 100, 550, value1);
  checkAndRemove(values3, 250, 750, value1);
  checkAndRemove(values4, 500, 1000, value1);

  index := random(values2.Count);
  value2 := values2[index];

  checkAndRemove(values3, 250, 750, value2);
  checkAndRemove(values4, 500, 1000, value2);

  index := random(values3.Count);
  value3 := values3[index];

  checkAndRemove(values4, 500, 1000, value3);

  index := random(values4.Count);
  value4 := values4[index];

  values1.Free;
  values2.Free;
  values3.Free;
  values4.Free;
end;

 

[Stefan Glienke 1905]

RandomRange - just saying

[corneliusdavid 142]

3 hours ago, Stefan Glienke said:

RandomRange - just saying

Well isn't that handy? How long has that been around? Found it back to at least 10 Seattle...

[Remy Lebeau 1260]

9 hours ago, corneliusdavid said:

Well isn't that handy? How long has that been around? Found it back to at least 10 Seattle...

RandomRange() has been around since Delphi 6.

Edited December 10, 2023 by Remy Lebeau

[Remy Lebeau 1260]

13 hours ago, Stefan Glienke said:

RandomRange - just saying

And RandomFrom()

 

[corneliusdavid 142]

31 minutes ago, Remy Lebeau said:

since Delphi 6.

And I've probably used it sometime in the past--and forgotten about it. (*head slap*)

[RTollison 0]

holy crap thank you all again. you really don't know how much i appreciate this. beein fighting a bad sinus/ear infection and am way too tired to be using what little of my brain is functioning. 

thank you , thank you, thank you.