Lottery App - More Efficient Method

[Stuart Buchan]

Hi Guys/Gals

As the Euromillions Lottery is sitting at £63M tonight, I thought I'd pop up my amended Lotto App (.aia) - original taken from Mike McGrath's "Building Android Apps no coding required!" book. His (.aia attached) was for the UK Lottery, mine is for Euromillions.

I just duplicated his blocks but changed the elements to suit and to accommodate the additional draw of two stars. I've tried to do this in a loop with variables changing using If-Then-Else blocks for main balls and stars but I didn't get the results I expected or it went into a never-ending loop.

I'm sure there must be a way of doing this more efficiently. I'm also planning to give the user a choice between UK & EuroMs games or do both. I'd be grateful for any suggestions.

BTW: If anybody uses this and wins with the generated numbers, an acknowledgement of yours truly would be brilliant! ;-)

Cheers, Stuart

[Abraham Getzler]

You shuffle a list of 49 items, using one pass to load 49 numbers

and a second pass to shuffle it.

The attached app should run about 10 times faster,

on the average.

ABG

[Stuart Buchan]

(Re-)posted here, as inadvertantly sent to Abraham's email, as I replied on  my phone!

Thanks Abraham!

That's great advice for the basic Lotto selection. My query was about how to use the same procedure to select a separate set of numbers (as per my EuroMs.aia).

I tried a For loop with an If-Then-Else block, using a variable as the number but nothing worked. I set the variable then changed it after the first iteration but I either got a never-ending loop or a 1-5 sequence for the first set and a random selection for the second set. I tried a While block too but got similar results.

I'll have another go and post my attempts, unless you or others can suggest how to achieve my goal in the meantime.

TIA

Stuart

[Abraham Getzler]

Can you describe for us how the EuroMillions lottery works?

I see 7 Labels for number choices.

For each Label, what is the range of numbers that can go in it?

Are duplicate values allowed?

ABG

[Chris Ward]

Five 'main' numbers, selected from 1-50. Two 'lucky stars' selected from 1-12. Numbers in the 'luck stars' can duplicate numbers in the 'main'.

[Abraham Getzler]

Two 'lucky stars' selected from 1-12. Numbers in the 'luck stars' can duplicate numbers in the 'main'.

Can the two lucky stars duplicate each other?

ABG

 

[Abraham Getzler]

See attached.

I assumed no duplication within the lucky stars.

ABG

[Chris Ward]

Assumption correct :)

[Stuart Buchan]

Briliant Abraham!

I actually managed to get it to work using a procedure and passing variables to it (see attached) but your solution is fantastic and so neat and tidy. WOW!

Cheers, Stuart

[Stuart Buchan]

Thanks for pointing out that it was a 1-50 selection for the first five numbers, Chris!

My .aia was therefore incomplete and not a valid option to play the Euromillions that night. ;-)

[SteveJG]

Are you aware your  Random Number isn't random; it is pseudo-random.  JDK1.7 doc says :Returned values are chosen pseudorandomly with (approximately) uniform distribution from that range.   Setting a random seed using the  random set seed to    block and setting to a day number so it changes every day might improve randomness (or using a different method to provide a different seed when the app is run.... day number plus the Clock now seconds perhaps?)..

See http://appinventor.mit.edu/explore/ai2/support/blocks/math.html  

random set seed to

Use this block to generate repeatable sequences of random numbers. You can generate the same sequence of random numbers by first calling random set seed with the same value. This is useful for testing programs that involve random values.

If you keep changing the seed, the numbers are no longer repeatable. With a seed you can generate the same results and by using different seeds , you can guarantee that a different number sequence will be generated.

Does it makes a difference?  I have no idea.  Perhaps others will comment.

Regards,

Steve

[Stuart Buchan]

Thanks Steve!

Great info. I'll remember that for testing in future and making the RNG more sophisticated.

Cheers, Stuart

[Stuart Buchan]

Hi

Please see the attached image of my Clear block.

Is it possible to create a procedure to set the labels to nulls by using "Label" and then appending 1-13 in a loop?

Cheers, Stuart

[Abraham Getzler]

See my https://docs.google.com/document/d/1RbPhI6cnHz3pRfqpEOVtRoMdkQlEA3Qm5BtuYq4bbGY/edit?usp=sharing

sample for how I use the Any Button blocks to scroll 3 buttons through a list of .Text values and button colors.

Notice the buttons value procedure I included to return a list of all my buttons.

You would need a Labels procedure for your labels, and the Any Label blocks.

They are in a separate section of the Blocks palette.

Post your latest .aia if you need a sample.

ABG

[Chris Ward]

Hello Stuart

If you are only going to loop the Labels to clear them, there is not really any advantage in having a loop as you still have to create a list of the labels at runtime to enable that loop.

[Stuart Buchan]

Thanks Chris! I wondered about that. ;-)

[Stuart Buchan]

Thanks again Abraham. I'll check it out.

Chris pointed out that there would be no real advantage to clearing them with a loop. I just thought I could use the number sequence something like this :

For i=1 to 13

  set "Label" & i to " "

Next i

Cheers, Stuart

[Italo]

I really wish somebody would add a StringToComponent block, so we can "construct" the component ID name by joining strings.

May be some extension developer...

Stuart, Chris is right, you can do it by creating a list of components ID's but in the end it will be the same amount of work if you only do it to clear their contents.

If you still decide you want to do it, Taifun once showed us a way to do it, by using the "Lookup in Pairs" block.

Basically you create a list of lists. Each "sublist" has the string and the component ID.

You search for the key any way you want (by joining strings for example) and you get the component ID.

[Abraham Getzler]

You are doing more than clearing your labels, right?

You are also loading them from matching list elements after 

generating your random numbers.  

That would pay for the list of labels procedure block count.

for i = 1 to length of list (call all_labels)

  set Label.Text of (select item i from list (call all_labels)) to select item i from list picks

end for

ABG

[Stuart Buchan]

Spot on Abraham!

[Boban Vukovic]

I made this app some time ago and it may be interesting because it uses sprites and sorts numbers at the end.

PS balls spacing (size) is not adjusted (it is for my screen size !) so  there might be some overlapping or under sizing for different screen sizes 

[Stuart Buchan]

Hi Steve

I'm interested in using this "random set seed to" block but can't discover how to utilise it.

My assumption is that it overrides the built-in pseudo RNG procedures with the seed being set first. So If I apply any other random block afterwards, it will use the seed to generate the number. Is that correct?

If that is the case, I can't see how to connect the seed block to another random block. If not, how does it work?

Any examples?

Cheers, Stuart

[SteveJG]

I do not think the block overrides the pseudo random distribution, it only adds an additional layer of randomness or repeatability depending on how it is used.  It seems if you use it with a static seed, your app should repeat every time you start fresh.  If you change the seed (presumably with a pseudo random number... something like the current time in seconds) it should start with a different seed if the block is placed as the initial block in your routine that calls for a random number.   Does it really provide a real random number?  No.  What it does is adds an additional 'layer' of randomness. I can't prove that.

[Stuart Buchan]

Hi Steve

I worked out how to use it and have created this block to test it. To ensure that the seed worked, I input a value instead of the Clock1 block and it repeated every time Button1 was pressed.

This random seed method works a treat!

Cheers, Stuart

[SteveJG]

Glad that works the way you want.  Thanks for posting your blocks so others can see how you did it.

[Stuart Buchan]

No problem Steve. In fact, here's the .aia with modifications. There are a few more I'd like to make but thus far, I'm happy with it.

Suggestions for improvements most welcome!

Cheers, Stuart

[Stuart Buchan]

Love it Boban!

I had thought about doing something similar. I've already started doing some of the ball images on Photoshop.

I'll look at your blocks for some ideas ;-) !

Cheers, Stuart

[Boban Vukovic]

actually I stole (borrowed!) my balls images from Finish(like Finland) lottery

[Boban Vukovic]

One more thing,if you are adding random numbers to a list and then generate next number,check if it is in list,if it is,generate another one... In my opinion you loose a bit of "randomness"!

Much better to remove random number from a list,and generate another one only from numbers remaining.

and set seed to seconds,or even better milliseconds from system clock 

[Abraham Getzler]

if you are adding random numbers to a list and then generate next number,check if it is in list,if it is,generate another one... In my opinion you loose a bit of "randomness"!

Much better to remove random number from a list,and generate another one only from numbers remaining.

Uh oh, are you bringing up the Monty Hall problem?

This is way beyond my pay grade.

ABG

[Boban Vukovic]

Never heard for that problem before,but explanation is fascinating!

PS what if I love goats?

[Italo]

About taking the numbers from a single pool to avoid the problem mentioned above, here’s a procedure I made some time ago to create a list of random numbers, with these options

Minimum
Maximum
How many numbers
Repeat or unique numbers
Sorted or unsorted
Sort order ascending or descending

[Stuart Buchan]

Nice one Italo!
Cheers, Stuart

[Stuart Buchan]

Hi Italo

How did you create that procedure? I just want to sort and nothing else, so wanted to recreate your "Function" procedure without the other options.

I have managed to do it using existing blocks (see attached sort block image) but I'd love to be able to create Function blocks like yours, as I've used functions in other programming methods previously.

Cheers, Stuart

[Stuart Buchan]

Hi Boban

I took your advice and added an additional seed in my block (see image below)

Cheers, Stuart

[Italo]

It's a simple bubble sorting procedure.

Use this one with parameters instead. It will be easier to reuse in the same app or in other projects later.

Also specify "a" for ascending or "d" for descending.