[Gambas-user] A random sort of listview

[jbskaggs]

Okay,

But why does it do that?  I don't see why the direction should matter what
am I missing ?  Becuase maybe this is something that has plagued me and
caused me headaches for a while.

JB Skaggs




Simonart Dominique wrote:
> 
> Hi,
> 
> jbskaggs a écrit :
>> When I ran the code it ran fine- why is it important to have it  count
>> backwards in the random swap?
>> 
>> ie for i =199 to 0 step -1 instead of for i=0 to 199 step 1?
>> 
>> JB SKaggs
>> 
> Strange, because it should not  :)
> run a test with 10 numbers 0-9 and fixe the seed with 
> RANDOMIZE 12345
> If you run the forward FOR NEXT you will get:
> 0 0 2 3 1 1 2 6 3 8
> which is wrong!
> but if you run the backward FOR NEXT you will get:
> 5 1 9 6 0 3 8 7 2 4
> which is right!
> 
> May be you did not notice it because 200 is long enough 
> before you get the same number twice, and before you remark 
> that some are missing?
> 
> Dominique Simonart
> 
>> 
>> Simonart Dominique wrote:
>>> Hi,
>>>
>>> Hmm, did you run exactly this code? If so, there is 
>>> something wrong with the second FOR NEXT loop
>>>
>>> jbskaggs a écrit :
>>>> using your suggestions and the swap command vs manual swapping this is
>>>> my
>>>> code:
>>>>
>>>> public b as string  'optional string used to hold the array data for
>>>> file
>>>> or
>>>> split later
>>>>
>>>> PUBLIC SUB button4_click() ' initialize array
>>>> DIM myArray AS Integer[200]
>>>> DIM a AS Integer
>>>> DIM i AS Integer
>>>>
>>>> FOR i = 0 TO 199 STEP 1 'add array items 
>>>>  myArray[i] = i 
>>>> NEXT 
>>>>
>>>> FOR i = 0 TO 199 STEP 1 ' random swap array items
>>>> a = Int(Rnd(i + 1))
>>>> SWAP myArray[i], myArray[a]
>>>> NEXT 
>>>>
>>> the right code is:
>>>
>>> FOR i = 199 TO 0 STEP -1
>>>     ...
>>> NEXT
>>>
>>>> FOR i = 0 TO 199 STEP 1 ' write items in listview2
>>>> listview1.MoveTo(myArray[i])
>>>> c = listview1.Item.Key
>>>> listview2.add(c, listview1.item.text) 
>>>> NEXT 
>>>>
>>>>
>>>>
>>>> FOR i = 0 TO 199 STEP 1 'optional step to write array as a string for
>>>> file
>>>> or whatever use
>>>> b &= "slot" & myArray[i] & ","
>>>> NEXT 
>>>> PRINT b
>>>> END
>>>>
>>>> PUBLIC SUB Button1_Click() 'an optional way to load the array values
>>>> from
>>>> the variable b and / or a file if b was file loaded
>>>> DIM egg AS String[]
>>>> DIM c AS String
>>>>  listview1.Clear
>>>>  egg = Split(b, ",")
>>>>  FOR EACH c IN egg 
>>>> TRY listview1.Add(c, c) 
>>>> IF ERROR THEN RETURN 
>>>> NEXT 
>>>> IF listview1.Count >= 200 THEN RETURN 
>>>> END
>>>>
>>>> JB Skaggs
>>>>
>>> Dominique Simonart
>>>
> Dominique Simonart
> 
> 
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