do you seed the random number generator somewhere at first?

Did you seed the random generator at the start of your app like I showed you? Plus that dummy call of math.random?

So no dummy call. There is a topic here on the forum, that the the first math.random call is always the same. That is why I posted about the dummy call.

Here is the code. With the second line commented out, it shows the same number every time in the Simulator/terminal (99).

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math.randomseed(os.time())
--dummy = math.random(0,255)
a = math.random(150)
print(a)

Tom

Hasufel,

There is absolutely no need to re-seed like that. It actually makes your random numbers *less* random. I posted about this in a different thread when we were discussing the original issue a while back, but here's the short version:

1) Rand is an algorithm. It generates pseudo random numbers based on the seed given it.
2) Each time you feed it a different seed, you restart the random algorithm itself, in effect, you are taking the first number in a random sequence each time you call your "getRandom" function. This is not how the algorithm is intended to work and by doing it this way you actually make things less random.
3) The workaround is exactly as Mike posted. You seed once at the start of your app (with os.time()), then you immediately follow that with a dummy call to math.random(). From that point forward, you will get the correct random numbers.

The only time you should want to "re-seed" is if you are wanting to run the same sequence. This is often desirable to reproduce the same path previously. For instance, if you had a game where the setup was based on random numbers (like a sudoko or something), if you save the seed you use to create the board, then you can regenerate that board again just by setting the seed to the same number. The only gotcha is if you change any of the code so you don't utilize the random numbers in the same way.

At any rate, the point is, don't re-seed, that's a bad practice and totally unnecessary. Seed once, make a dummy math.random call, and you're good to go.

Scott

No problem. This oddity about math.random should be mentioned inside the App Programming Guide in big bold letters :-)

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math.randomseed(os.time());
math.random();
 
for i = 1, 10 do
    print(i..") "..math.random());
end

Every time I reload I get different numbers for all 10.

Simple tests like this put at the top of your main.lua can easily show you if you are making a mistake in your code or if it's an issue with lua.

Scott

Trying not to smile too much. :)

That's not how random works.

From lua.org Reference document:
----
math.random ([m [, n]])

This function is an interface to the simple pseudo-random generator function rand provided by ANSI C. (No guarantees can be given for its statistical properties.)

When called without arguments, returns a uniform pseudo-random real number in the range [0,1). When called with an integer number m, math.random returns a uniform pseudo-random integer in the range [1, m]. When called with two integer numbers m and n, math.random returns a uniform pseudo-random integer in the range [m, n].
----

First off, the dummy call is a dummy call. No need to pass anything to it.

Second, here's the loop you ran through:

Loop 1: Give me a random number between 1 and 1.
Loop 2: Give me a random number between 1 and 2.
Loop 3: Give me a random number between 1 and 3.
Loop 4: Give me a random number between 1 and 4.
Loop 5: Give me a random number between 1 and 5.
Loop 6: Give me a random number between 1 and 6.
Loop 7: Give me a random number between 1 and 7.
Loop 8: Give me a random number between 1 and 8.
Loop 9: Give me a random number between 1 and 9.
Loop 10: Give me a random number between 1 and 10.

Take the "i" out of the math.random call and replace it with the range you want. It sounds like you want a number between 1 and 10, so that would be math.random(10).

Scott

Well, there's a syntax error in the code you put here, but here's what I ran... it differs only in that it displays a text string instead of your image:

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math.randomseed(os.time());
math.random();
 
myList = {
        "alex.jpg",
        "eric.jpg",
        "marina.jpg",
};
textY = 20;
 
function selectRandom()
        local rand = math.random(#myList);
        local tFile = myList[rand];
        local nt = display.newText(tFile, 20, textY, nil, 12);
        textY = textY + 20;
        nt:setTextColor(255, 255, 255);
        table.remove(myList, rand);
end
 
selectRandom();
selectRandom();
selectRandom();

You must remember, this is a very small sample of images. Your chances are 1 in 3 of always getting 1. That never changes no matter how many times you run this app. You always have a 33% chance to get 1 as you first number.

I did want to complement you on your method for not getting a recurring image. :)

At any rate, the code works. You will get different starting numbers. But you'll also get repeats.

Yes, the results were from running it on my iPhone as well as on the simulator.

Scott

No problem, Alex. I've no problem helping folks who are honestly giving it a good try before just coming here and asking for folks to write it for them. :)

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math.randomseed = ( os.time() )

Should be:

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math.randomseed( os.time() )

You use <code> and </code> around your code block.

If you really do have the above error in your code, then it could be the culprit.

With a sample set of 130 elements, something else is wrong.

Did you run my code above? If I had to guess, you've got a logic error somewhere in how you're getting your random element.

Bottom line, if you take the code I posted previously and run it (simulator and on your iphone) you'll see the random functionality working. With only 3 elements you *do* get the same list sometimes, but if you run it 5-10 times you'll see you get different lists.

Just like if you take the code I posted previously which generates 10 random numbers you'll see that works exactly as it's supposed to.

I advise you take the code posted here and try it out in a separate project, then go back and look at your code again and figure out what you're doing wrong.

Scott