[SOLVED] PHP to select chance - 50% of time X - 50% of time Y

[doa24uk]

Hi guys,

 

I'm sure this is very simple, and I believe has something to do with generating random numbers (although I could be wrong).

 

What I need is simple, code that will show picture X 50% of the time, and picture Y 50% of the time. So that  the views on each picture will be exactly the same.

 

Can this be achieved? Thanks in advance

 

DoA

[kael.shipman]

Random indeed:

 

<?php
$pictures = array('src/of/pic1.jpg','src/of/pic2.jpg');
$showPic = $pictures[rand(0,1)];
?>

[pocobueno1388]

Random indeed:

 

<?php
$pictures = array('src/of/pic1.jpg','src/of/pic2.jpg');
$showPic = $pictures[rand(0,1)];
?>

 

That would randomly generate one of the images....which would mean they would not be shown 50% evenly.

 

[kael.shipman]

You're talking about showing pic1.jpg on 50% of pageloads and pic2.jpg on the other 50% of pageloads?

 

If you don't care what order they show in, then probability surely does dictate that a random selection between 0 and 1 will produce "1" 50% of the time and "0" the remaining 50% of the time, which means that if you use that to select an image source, pic1.jpg will indeed show on 50% of pageloads and pic2.jpg will show on 50% of pageloads.

 

Maybe I missed the question? What does "shown 50% evenly" mean?

[cooldude832]

Make a flat file that stores a value last image shown and open it and each time switch the value if you want "50/50" or use a mysql table line

[pocobueno1388]

Are you wanting these images to show up evenly for each specific user, or just by click? If it is by click, I would suggest just making them show up randomly and not worry about if it is being shown evenly.

 

If you are wanting to make sure it shows up evenly for each specific user, then you are going to have to use a database to keep track of which one the user saw last.

[AndyB]

Do understand that random choice between two alternatives will not produce what you want except over an enormous number of iterations.

 

If you flip a coin and it lands heads up, will the next flip be tails?  No, it'll be random because the coin has no memory of what happened before and heads is equally as likely as tails.

 

The only way to show 'the other picture' the next time is to know what picture was seen last time - and that means storing information (flat file, cookie, database).

[doa24uk]

Yes, sorry I should have clarified;

 

They don't have to show up sequentially by 50% (a,b,a,b,a etc.) they can indeed by (a,a,b,b,b,a)

 

So the first example will work great, thanks!