Help with Randomization of Non-Overlapping Images

[tamiskovich at gmail.com]

Hi David,

Thank you so much for your reply. I know the thing is a visual nightmare at 
the moment and needs a little aesthetic touch up. Sorry! 

These are incredibly helpful suggestions and getting me to think about this 
a lot deeper.

The only issue with the array, while it would be easier, is that 1. It 
seems like I could still have some over lap since my images are 2x3 % in 
eprime and 2. ideally I would like to still be able to use the same x 
coordinate for two images just so long as they don't overlap (they are far 
enough apart on the y).

So it's really tricky since I need to consider a range of coordinates when 
I place an image to insure they do not overlap. 

I like the idea of the 2 dimensional array (sounds tricky) cause that would 
solve #1 but not sure how to get around #2 and ensuring they don't overlap 
+ or - 2 or 3 values.

Thanks again so much for the help!

On Monday, August 4, 2014 2:01:56 PM UTC-5, McFarlane, David wrote:
>
> Tara, 
>
> Wow, that Loop While statement just hurts my eyes!  When something 
> gets that complicated, I would at least try to format it better for 
> readability (indentation and the "_" continuation character are your 
> friends here), or better yet find some way to restructure the code so 
> as to avoid such a long expression.  E.g., if you used some arrays 
> instead of simple variables then you could use a loop or two to run 
> through all those tests that appear explicitly in your While expression. 
>
> So I do not know if something goes wrong with your code per se.  But 
> your approach here reminds me of a bogosort (see 
> http://en.wikipedia.org/wiki/Bogosort ), and it may suffer from the 
> same problem.  Even with no errors in the code, the code must find a 
> solution *by chance*, and *by chance* that may take many tries.  That 
> may work well enough for small problems, but as the proportion of 
> solutions in the problem space gets smaller this approach takes 
> longer and longer to find one.  In particular, perhaps for 3 
> coordinates your "bogosort" code could quickly find a solution, but 
> for 4 images it just takes a lot longer to find one *by 
> chance*.  (PST's own "No Repeats on Consecutive Trials" examples, 
> download from their website, suffer the same problem.) 
>
> I do not like algorithms that work by chance, so I avoid them 
> whenever possible.  So first let's restate your problem, and see what 
> we can do. 
>
> You want to find 4 unique, randomly chosen x values from a pool of 7 
> values, and 4 unique, randomly chosen y values from a pool of 23 
> values.  IOW, you want to pick 4 x values randomly without 
> replacement from the range [36, 42], and 4 y values randomly without 
> replacement from the range [38, 62].  Did I get that right? 
>
> Ideally, you would follow David V's advice, make a nested List with 
> all possible (x, y) pairs and just pick from that (Random, without 
> replacement).  That should involve 7 x 23 = 161 rows, which would not 
> be too much trouble, and Excel would make it even easier to construct 
> such a List.  Alternatively, you might use two nested Lists, one for 
> all the x values and another for all the y values, each Random 
> (without replacement) and pick from those. 
>
> But if you like inline code, I might start by making a couple arrays 
> to hold my pools of x & y values: 
>
>      Const xPoolSize as Integer = 7, xPool1 as Integer = 36 
>      Const yPoolSize as Integer = 23, yPool1 as Integer = 38 
>      Dim i as Integer 
>      Dim xPool( 1 to xPoolSize ) as Integer 
>      Dim yPool( 1 to yPoolSize ) as Integer 
>      xPool(1) = xPool1 
>      For i = 2 to xPoolSize 
>          xPool(i) = xPool(i-1) + 1 
>      Next i 
>      yPool(1) = yPool1 
>      For i = 2 to yPoolSize 
>          yPool(i) = yPool(i-1) + 1 
>      Next i 
>
> With a little trouble you could compact that code even better by 
> using a 2-dimensional array for x & y together, although then the 
> next step would not work.  I leave that as an exercise. 
>
> Next, just shuffle these arrays.  VBA/E-Basic provides a command just 
> for this (but only for 1-dimensional arrays, sigh): 
>
>      RandomizeArray xPool 
>      RandomizeArray yPool 
>
>
> You may find RandomizeArray documented in the E-Basic Help facility. 
>
> Now you may simply pick the first 4 values from the xPool & yPool 
> arrays to construct your coordinates. 
>
> Does that look like it will work?  What have I missed? 
>
> ----- 
> David McFarlane 
> E-Prime training 
> online:  http://psychology.msu.edu/Workshops_Courses/eprime.aspx 
> Twitter:  @EPrimeMaster (https://twitter.com/EPrimeMaster) 
>
> /---- 
> Stock reminder:  1) I do not work for PST.  2) You may reach PST's 
> trained staff (and other support facilities) at 
> https://support.pstnet.com .  3) If you do get an answer from PST 
> staff, please extend the courtesy of posting their reply back here 
> for the sake of others. 
> \---- 
>
>
> At 8/1/2014 05:43 PM Friday, tamis... at gmail.com <javascript:> wrote: 
> >Thanks for your response David. That is what I was afraid of. Eprime 
> >support said it should work in theory, but seems as though it keeps 
> >getting stuck when I add in the forth image. I am trying to list all 
> >the combinations as well, it is just proving to be a huge task, for 
> >there are an enormous amount of possible combinations. 
> > 
> >I was hoping that this would make coding much quicker and truly random. 
> > 
> >Tara 
> > 
> >On Friday, August 1, 2014 12:54:35 PM UTC-5, Vinson, David: UCL wrote: 
> >I suspect you didn't get any replies before due the impressively 
> >complicated set of OR statements in that loop. I suspect the problem 
> >is there somewhere but imagine it world be a nightmare to track it 
> >down. My guess is the loop never exits, whether due to an error or 
> >impossible constraints. 
> > 
> >What if instead you enumerated the possible legal combinations of 
> >positions in a nested List and then just sampled one of them per trial? 
> > 
> >Good luck, 
> >David V 
> > 
> >----- Reply message ----- 
> >From: "tamis... at gmail.com" <tamis... at gmail.com> 
> >To: "e-p... at googlegroups.com" <e-p... at googlegroups.com> 
> >Subject: Help with Randomization of Non-Overlapping Images 
> >Date: Fri, Aug 1, 2014 6:30 pm 
> > 
> > 
> > 
> >Does anyone have any suggestions on this? I'm stuck on this and 
> >eprime support directed me here. 
> > 
> >Tara 
> > 
> >On Monday, July 28, 2014 3:43:33 PM UTC-5, Tara Miskovich wrote: 
> >Hello, 
> > 
> >I am working on having 4 images randomly places within a rectangular 
> >region without overlapping. I wrote the code below, and it appears 
> >to be working with up to Image 3 added, but when I add in the forth 
> >image the program freezes. I am hoping for some guidance with what 
> >to try next or how to get past this. Here is the code I wrote to 
> >randomize the x and y location for each image. 
> > 
> >Thanks! 
> >Tara 
> > 
> >Dim x1 As Integer 
> >Dim x2 As Integer 
> >Dim x3 As Integer 
> >Dim x4 As Integer 
> >Dim y1 As Integer 
> >Dim y2 As Integer 
> >Dim y3 As Integer 
> >Dim y4 As Integer 
> > 
> >x1 = random(36, 42) 
> >y1 = random(38, 60) 
> > 
> >Do 
> >x2 = random(36, 42) 
> >y2 = random(38, 60) 
> >x3 = random(36, 42) 
> >y3 = random(38, 60) 
> >x4 = random(36, 42) 
> >y4 = random(38, 60) 
> > 
> > 
> >Loop While (x2 = x1 Or x2 = x1 + 1 Or x2 = x1+2 Or x2 = x1 - 1 Or x2 
> >= x1 - 2 _ 
> >And y2 = y1 Or y2 = y1 + 1 Or y2 = y1 + 2 Or y2 = y1 + 3 Or y2 = y1 
> >- 1 Or y2 = y1 - 2 Or y2 = y1 - 3)_ 
> >Or (x3 = x1 Or x3 = x1 + 1 Or x3 = x1+2 Or x3 = x1 - 1 Or x3 = x1 - 2 _ 
> >And y3 = y1 Or y3 = y1 + 1 Or y3 = y1 + 2 Or y3 = y1 + 3 Or y3 = y1 
> >- 1 Or y3 = y1 - 2 Or y3 = y1 - 3)_ 
> >Or (x3 = x2 Or x3 = x2 + 1 Or x3 = x2+2 Or x3 = x2 - 1 Or x3 = x2 - 2 _ 
> >And y3 = y2 Or y3 = y2 + 1 Or y3 = y2 + 2 Or y3 = y2 + 3 Or y3 = y2 
> >- 1 Or y3 = y2 - 2 Or y3 = y2 - 3)_ 
> >or (x4 = x1 Or x4 = x1 + 1 Or x4 = x1+2 Or x4 = x1 - 1 Or x4 = x1 - 2 _ 
> >And y4 = y1 Or y4 = y1 + 1 Or y4 = y1 + 2 Or y4 = y1 + 3 Or y4 = y1 
> >- 1 Or y4 = y1 - 2 Or y4 = y1 - 3)_ 
> >Or (x4 = x2 Or x4 = x2 + 1 Or x4 = x2 + 2 Or x4 = x2 - 1 Or x4 = x2 - 2 _ 
> >And y4 = y2 Or y4 = y2 + 1 Or y4 = y2 + 2 Or y4 = y2 + 3 Or y4 = y2 
> >- 1 Or y4 = y2 - 2 Or y4 = y2 - 3)_ 
> >Or (x4 = x3 Or x4 = x3 + 1 Or x4 = x3 + 2 Or x4 = x3 - 1 Or x4 = x3 - 2 _ 
> >And y4 = y3 Or y4 = y3 + 1 Or y4 = y3 + 2 Or y4 = y3 + 3 Or y4 = y3 
> >- 1 Or y4 = y3 - 2 Or y4 = y3 - 3) 
> > 
> >c.SetAttrib "x1", x1 
> >c.SetAttrib "x2", x2 
> >c.SetAttrib "x3", x3 
> >c.SetAttrib "x4", x4 
> >c.SetAttrib "y1", y1 
> >c.SetAttrib "y2", y2 
> >c.SetAttrib "y3", y3 
> >c.SetAttrib "y4", y4 
>
>

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