Android Question random number except of one number...

Gunther

Active Member
Licensed User
yes, not directly as you suggest, but do it with a loop:

B4X:
Dim intNewNumber As Int = Rnd(1, 10)
'
Do Until  (intNewNumber <> 2 or intNewNumber <> 5)
 
     intNewNumber = Rnd(1, 10)
 
Loop
'
If the Number is 2 or 5 a new RND is taken.
 

sorex

Expert
Licensed User
something like this?

B4X:
dim r as int
r=2 ' might be needed to bypass an extra rnd call
do while r=2 or r=5
r = rnd(1,10)
loop
 

ilan

Expert
Licensed User
i made allready that kind of function but it makes my game flicker a little



B4X:
sub selectlevel
Dim lv As Int = randomfunction(maxlevels,pnl1.Tag)
end sub

'....
Sub randomfunction(maxint As Int,forbiddennr As Int) As Int

Dim rnd1 As Int = forbiddennr
Do Until rnd1 <> forbiddennr
    rnd1 = Rnd(2,maxint)
Loop
Return rnd1

End Sub
 

JordiCP

Well-Known Member
Licensed User
Do the random for maxint minus one, and add one if the result is equal or more than forbiddennr

B4X:
Sub randomfunction(maxint As Int,forbiddennr As Int) As Int
   Dim rnd1=Rnd(1,maxint-1)
   if rnd1>=forbiddennr then
      rnd1=rnd1+1
   end if
End Sub
 

sorex

Expert
Licensed User
if the range is big enough you could risk

B4X:
dim r as int
r=rnd(1,10)
if r=2 or r=5 then r=rnd(1,10)
which should use less resources
 

ilan

Expert
Licensed User
Do the random for maxint minus one, and add one if the result is equal or more than forbiddennr

B4X:
Sub randomfunction(maxint As Int,forbiddennr As Int) As Int
   Dim rnd1=Rnd(1,maxint-1)
   if rnd1>=forbiddennr then
      rnd1=rnd1+1
   end if
End Sub
what if the last number was = maxint then it can be that the same level will be loaded again
 

ilan

Expert
Licensed User
is the range static?
i have for example 10 levels

and i want load them randomly but i dont want a level appear twice
so i want to avoid the same level will be loaded again


i tried also

B4X:
Dim lv As Int = Rnd(2,maxlevels+1) 'choose random level except of level1 and same level
            If lv <> pnl1.Tag Then
                pnl2.LoadLayout("level" & (lv))
                pnl2.Tag = lv
            Else
                pnl2.LoadLayout("level" & Min((pnl1.Tag+1),maxlevels))
                pnl2.Tag =  Min((pnl1.Tag+1),maxlevels)
            End If
 

Gunther

Active Member
Licensed User
Well, here is an other one!

But the forbidden numbers need not be in a row, e.g. 2,3 or 6,7 and never 9!

B4X:
dim r as int
r=rnd(1,10)
if r=2 or r=5 then r = r + 1
This is faster but not that flexible as my first one.
 

Gunther

Active Member
Licensed User
what you mean by ?

"...load them randomly but i dont want a level appear twice..."


1) all 10 levels shall be used once and than never again?
2) or not directly after a level is done?

for 1) you may shuffle the number in the beginnig and doing a list from 1 to 10
for 2) see #14 or #2
 

ilan

Expert
Licensed User
Well, here is an other one!

But the forbidden numbers need not be in a row, e.g. 2,3 or 6,7 and never 9!

B4X:
dim r as int
r=rnd(1,10)
if r=2 or r=5 then r = r + 1
This is faster but not that flexible as my first one.
this will not work
 

Troberg

Well-Known Member
Licensed User
Put the allowed numbers in an array, then simply pick an item from the array at random. Slower if you only need to do it occasionally, but if you need to do it often and can prepare the array in advance, it will be fast, and it will have a predictable running time, which the loop methods won't.
 

sorex

Expert
Licensed User
shuffle a level array at each game start

B4X:
Dim r As Int
Dim t As Int
Dim levels() As Int=Array As Int(1,2,3,4,5,6,7,8,9,10)
For x=0 To levels.Length-1
    r=Rnd(0,levels.Length)
    t=levels(r)
    levels(r)=levels(x)
    levels(x)=t
Next
Log(levels(0))
chances that the levels will be the same in a row az the previous game are very unlikely
 

ilan

Expert
Licensed User
what you mean by ?

"...load them randomly but i dont want a level appear twice..."


1) all 10 levels shall be used once and than never again?
2) or not directly after a level is done?

for 1) you may shuffle the number in the beginnig and doing a list from 1 to 10
for 2) see #14 or #2
i want the levels load randomly again and agian but not same level twice after he was loaded.
but he can be again loaded if another level was before

like 2,4,5,3,2,4,2,6,7,5,6,7,....
 

Troberg

Well-Known Member
Licensed User
Well, here is an other one!

But the forbidden numbers need not be in a row, e.g. 2,3 or 6,7 and never 9!

B4X:
dim r as int
r=rnd(1,10)
if r=2 or r=5 then r = r + 1
This is faster but not that flexible as my first one.
That would give skewed probabilities, where 3 and 6 are twice as likely to appear as the other numbers.
 
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