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There is probably either a Tutorial or a dupe I can read in order to figure this out, but I haven't been able to find one by searching on my own. So here is the problem:

I want to create a function checkboxToList[] that displays a grid of checkboxes like the following:

Column[Table[
  CheckboxBar[ConstantArray[0, alfa + 1], Range[-alfa, 3]]
  , {alfa, 5, 0, -1}
  ]
 , Alignment -> Right
 ]

enter image description here

Then I want the user to be able to make selections, like e.g.

enter image description here

Finally, by pressing a button or something similar, I want the function to return a list of pairs {{x1,y1},{x2,y2},...} where the x are the row numbers of the checked boxes counting from below, starting from 0, and the y are the checkbox labels. Thus, from the second image I would want to return {{0,0}, {0,1}, {2,-2}, {4,-4}, {4,-2}}. The order of the pairs in the returned list does not matter to me.

Any help much appreciated!

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  • 1
    $\begingroup$ CheckboxBar[ConstantArray[0, alfa + 1], Range[-alfa, 3]] is effectively the same as CheckboxBar[{0}, Range[-alfa, 3]]. $\endgroup$
    – Karsten7
    Sep 19, 2016 at 17:10

2 Answers 2

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checkboxToList[rows_] := DynamicModule[{cbb},
  cbb = ConstantArray[{0}, rows];
  Panel@Column[{
     Column[
      Table[
       With[{pos = alfa + 1}, 
        CheckboxBar[Dynamic[cbb[[pos]]], Range[-alfa, 3]]], {alfa, rows - 1, 
        0, -1}]
      , Alignment -> Right]
     ,
     Button["Checkboxes to List",
      CellPrint@ExpressionCell@Flatten[
         Transpose[{Range[0, Length@cbb - 1], 
            cbb}] /. {{a_, {b__}} :> ({a, #} & /@ {b}), {a_, {}} -> Nothing},
         1]]
     }]
  ]

checkboxToList[6]

OutGif

Edit 1:

SetAttributes[checkboxToList, HoldAll]

checkboxToList[rows_, out_] := 
 DynamicModule[{cbb}, cbb = ConstantArray[{0}, rows];
  Panel@Column[{Column[
      Table[With[{pos = alfa + 1}, 
        CheckboxBar[Dynamic[cbb[[pos]]], Range[-alfa, 3]]], {alfa, rows - 1, 
        0, -1}], Alignment -> Right], 
     Button["Checkboxes to List", 
      out = Flatten[
        Transpose[{Range[0, Length@cbb - 1], 
           cbb}] /. {{a_, {b__}} :> ({a, #} & /@ {b}), {a_, {}} -> Nothing}, 
        1]]}]]

checkboxToList[6, ans]

Edit 2:

checkboxToList[rows_] := DynamicModule[{cbb}, cbb = ConstantArray[{0}, rows];
  Panel@Column[{Column[
      Table[With[{pos = alfa + 1}, 
        CheckboxBar[Dynamic[cbb[[pos]]], Range[-alfa, 3]]], {alfa, rows - 1, 
        0, -1}], Alignment -> Right], Button["Checkboxes to List",
      MakeExpression[NotebookRead[PreviousCell[]], StandardForm] /. 
        HoldPattern[{__, out_ = checkboxToList[_]}] :> (out = 
           Flatten[Transpose[{Range[0, Length@cbb - 1], 
               cbb}] /. {{a_, {b__}} :> ({a, #} & /@ {b}), {a_, {}} -> 
               Nothing}, 1]) // ReleaseHold]}]]

ans = checkboxToList[6]
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5
  • $\begingroup$ I interpreted "return a list of pairs" as printing it as an ExpressionCell, but one can change that to whatever is most appropriate in the context of that function. $\endgroup$
    – Karsten7
    Sep 19, 2016 at 17:28
  • $\begingroup$ How would you change the Button expression so that, if I input ans = checkboxToList[6] in the notebook, the variable ans would have the list of pairs stored after pressing the button? Is this possible to do? $\endgroup$
    – Marius Ladegård Meyer
    Sep 19, 2016 at 19:15
  • $\begingroup$ @MariusLadegårdMeyer Please see my edit. Does that work for you too? ans = checkboxToList[6] would be possible to, but not necessarily in a way as obvious. $\endgroup$
    – Karsten7
    Sep 19, 2016 at 19:32
  • $\begingroup$ @MariusLadegårdMeyer I addet a version that works with ans = checkboxToList[6], but it's kind of an odd way. I'd prefer the version used in Edit 1. $\endgroup$
    – Karsten7
    Sep 19, 2016 at 20:18
  • $\begingroup$ Karsten 7., @andre, thank you both for contributing. My final implementation uses a hybrid of both your answers, so it's hard to chooce what answer to accept. I will accept Karsten 7.'s answer because it also taught me how to use the button in different ways. $\endgroup$
    – Marius Ladegård Meyer
    Sep 22, 2016 at 11:33
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Here is a solution that updates the list as soon as you check a box. 

(* myCheckbox add or remove "elt" to/from the list "choice" *)
SetAttributes[myCheckbox, HoldFirst];
myCheckbox[choice_, elt_] := 
 Checkbox[Dynamic[MemberQ[choice, elt], 
   If[#, AppendTo[choice, elt], choice = DeleteCases[choice, elt]] &]]

choice = {};
Dynamic[choice]

Column[Table[
  Row[Row [{myCheckbox[choice, {alfa, #}], #}, " ", 
      Alignment -> Left] & /@ Range[-alfa, 3], "    "], {alfa, 5, 
   0, -1}], Alignment -> Right]

enter image description here

choice

{{4, -4}, {4, -2}, {2, -2}, {0, 0}, {0, 1}}

Your approach with Column[Table[CheckboxBar ...]] has the drawback that if your checkbox labels have not the same size (vertically), your columns will be missaligned. This problem is solved if you use instead a Grid[] of the myCheckbox[] above. Example :

choice2 = {};
Dynamic[choice2]
Grid[{{Row[{myCheckbox[choice2, "A"], "A"}], 
   Row[{myCheckbox[choice2, "B"], "B"}]}, {, 
   Row[{myCheckbox[choice2, "C"], "CCCCC"}]}}, Alignment -> Left]

enter image description here

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