Finding Unique Values From An Array Randomly

phpprogrammer

Dear Friends,

I am having an array of employess with their employee numbers as follows


$arrEmp[0]='1';
$arrEmp[1]='2';
$arrEmp[2]='3';
$arrEmp[3]='4';
$arrEmp[4]='5';
$arrEmp[5]='6';
$arrEmp[6]='7';
$arrEmp[7]='8';
$arrEmp[8]='9';

---    $arrEmp[n]='n';

how can I pick 5 unique employee numbers randomly into a string.

The string should not contain the repeted employee numbers.

the string should be like 4,9,12,34 but not like 2,9,2,34

I did the same by using the while loop , is there any simple way

regards,
bvsureshbabu

rachel2004

Since you already know the minimum and maximum values in your array, just use the rand() function:

http://us3.php.net/manual/en/function.rand.php

LordShryku

[man]array_rand[/man]

rachel2004

Originally posted by LordShryku
[man]array_rand[/man]

Even better. ;-)

BuzzLY

For the record, rand() won't work for him, because it's possible to repeat array keys, and he specified that he does not want that to happen.

laserlight

I suppose [man]shuffle/man followed by picking the first n elements would be an alternative.

In any case, if it works well, why fix it?

BuzzLY

Heh... a fine example of the adage, "there's more than one way to skin a cat."

My guess is that internally, array_rand() uses the same algorithm as shuffle() and simply automatically returns the top n values.

Weedpacket

That would be my first implementation, too; but it would be bad if you were selecting three elements out of a thousand.

My second implementation would skip along the array, picking elements at random (with an appropriate probability) until I had enough - jumping back to the start if and when I need to. Then shuffle the elements I picked.

Maybe after I've had a coffee I'll think of a third 🙂