function call in a wrong place?

[imppi]

Hi

something not right in the code. whats the problem there with the inner while-loop?

global $num_of_elements = 35
global $shuffled_array[$num_of_elements]
global $orig_array[$num_of_elements] = [430, 428, 427, 427, 430, 432, 435,   438, 439, 439, 441, 437, 440, 440,  434, 438, 436, 433, 435, 440, 430,  444, 443, 444, 443, 446, 447, 448, 427, 426, 426, 426, 425, 424, 430]
global $j=0
global $i=0
shuffle_array()

func shuffle_array()
    For $k = 0 To $num_of_elements -1 Step 1
        $shuffled_array[$k] = 0
    next
    while $i < $num_of_elements
        while $shuffled_array[  $j=random(0, $num_of_elements-1, 1)  ] == 0
            $shuffled_array[$j]=$orig_array[$i]
            $i += 1
        WEnd
    wend
EndFunc

[PsaltyDS]

You can't do variable assignment inside the array index field: "$shuffled_array[ $j = Random(...) ]"

[imppi]

well thats a bummer.

[imppi]

got no warning or error. it just didn't work as i thought.

[PsaltyDS]

got no warning or error. it just didn't work as i thought.

You don't get an error because it's valid syntax, just not what you wanted. In a place in the script line where assignment is NOT valid (not at the begining of the line) it does comparison with the "=" operator. So "$j = random(0, $num_of_elements-1, 1)" returns True or False for the compare, it doesn't change the value to $j.

Of course a Boolean type is not a valid array index, but in most cases native AutoIt functions will re-type input variables as required, so the Boolean becomes either 0 (False) or 1 (True) and that's your index. No errors, but your array index will always be 0 or 1 based on the Boolean compare operation.

Demo:

Global $aArray[3] = ["A", "B", "C"]
Global $n = 1
ConsoleWrite("Result = " & $n & @CRLF)
ConsoleWrite("Result = ")
ConsoleWrite($n = 0)
ConsoleWrite(@CRLF)
ConsoleWrite("Result = ")
ConsoleWrite($n = 1)
ConsoleWrite(@CRLF)
ConsoleWrite("Result = " & $aArray[$n = 0] & @CRLF)
ConsoleWrite("Result = " & $aArray[$n = 1] & @CRLF)
ConsoleWrite("Result = " & $aArray[$n = 2] & @CRLF)

Edit: Typo

Edited November 11, 2009 by PsaltyDS

[GodlessSinner]

Global $array[10], $Elements = 9
;before shuffling
For $i = 0 to 9 Step 1
    $array[$i] = $i
    ConsoleWrite($array[$i])
Next
ConsoleWrite(@CRLF)

Shuffle($Elements)

;after shuffling
For $i = 0 to 9 Step 1
    ;$array[$i] = $i
    ConsoleWrite($array[$i])
Next
ConsoleWrite(@CRLF)
Func Shuffle($Elements)
    For $i = 0 To $Elements*2 Step 1
        $index1 = Random(0, $Elements, 1)
        $index2 = Random(0, $Elements, 1)
        $temp = $array[$index1]  ;instead of including Array.au3 and using _ArraySwap
        $array[$index1] = $array[$index2]
        $array[$index2] = $temp
        Next
EndFunc

[GodlessSinner]

In example listed above and _ArraySwap() used a $temp variable, but does know any one how to swap them WITHOUT creating temporary $var?

(It's possible and works faster, but i forgot how).

Edited November 11, 2009 by Godless

[martin]

In example listed above and _ArraySwap() used a $temp variable, but does know any one how to swap them WITHOUT creating temporary $var?

(It's possible and works faster, but i forgot how).

Don't be daft.

[imppi]

thanks for the clarification PsaltyDS. it worked just the way u described and it makes sense now. thanks for godless too for the fresh ideas too. That one seems much more efficient especially with a larger array.

[GodlessSinner]

Don't be daft.

IF $I'm_daft = TRUE then Show me temporary var:

Global $x = "20", $y = "314"

$x = BitXOR($x, $y)
$y = BitXOR($y, $x)
$x = BitXOR($x, $y)

MsgBox(0,$x & " " & $y, "")

Edited November 12, 2009 by Godless

[AdmiralAlkex]

IF $I'm_daft = TRUE then Show me temporary var:

Global $x = "20", $y = "314"

$x = BitXOR($x, $y)
$y = BitXOR($y, $x)
$x = BitXOR($x, $y)

MsgBox(0,$x & " " & $y, "")

Ans where is your proof that is faster?

[GodlessSinner]

#include <Timers.au3>

Global $x = "20", $y = "314", $starttime

$starttime = _Timer_Init()
For $i = 0 To 10000 Step 1
$z = $x
$x = $y
$y = $z
Next
ConsoleWrite(_Timer_Diff($starttime)& @CRLF)

$starttime = _Timer_Init()
For $i = 0 To 10000 Step 1
$x = BitXOR($x, $y)
$y = BitXOR($y, $x)
$x = BitXOR($x, $y)
Next
ConsoleWrite(_Timer_Diff($starttime)& @CRLF)

[AdmiralAlkex]

That was interesting.... Or maybe not.

Even after fixing that flaud test your BitXOR method was only HALF as fast as copying to a variable.

Global $x = "20", $y = "314", $starttime, $i

For $i = 0 To 10000000      ;Should be enough to trick Cool'n'Quiet, SpeedStep etc on most computers.
Next

$starttime = TimerInit()
For $i = 0 To 10000 Step 1
$z = $x
$x = $y
$y = $z
Next
$endtime1 = TimerDiff($starttime)

$starttime = TimerInit()
For $i = 0 To 10000 Step 1
$x = BitXOR($x, $y)
$y = BitXOR($y, $x)
$x = BitXOR($x, $y)
Next
$endtime2 = TimerDiff($starttime)

ConsoleWrite($endtime1 & "/" & $endtime2 & @CRLF)   ;Not sure if this was necessary

I bet that if we did this test on an array as the topic was on your method would be even slower, since working on arrays are far slower than working on variables.

Edit: I got around 16 ms vs 32 ms

Edit2: Clarification

Edited November 12, 2009 by AdmiralAlkex

[martin]

IF $I'm_daft = TRUE then Show me temporary var:

Global $x = "20", $y = "314"

$x = BitXOR($x, $y)
$y = BitXOR($y, $x)
$x = BitXOR($x, $y)

MsgBox(0,$x & " " & $y, "")

Well that doesn't use an extra variable so I must hastily admit defeat. However it does create an extra value but uses an existing variable so I'm going to treat it as a technical defeat but not a moral one. Not that I'm a sore looser or anything but it's just that I'm a, um, .. a sore looser.