CODEWITHSUNDEEP
user-interfacewolfram-mathematicamathematica-frontend
Cetin Sert
Cetin Sert

Reputation: 4590

Evaluate current cell without leaving or losing the position in it in Mathematica

I am experimenting with logo designs in Mathematica (8 or above) using the notebook interface and I want to change the generating formula A LOT. The problem is I only know SHIFT + ENTER which makes me jump outside my current cell and lose my position.

Is there a way to evaluate the current cell without leaving it and losing your position within it? So: Evaluate a cell and land back inside the same cell at the exact position I pressed SHIFT + ENTER at.

What I once came to use was along the lines:

a = Exp[1.994 \[Pi]/(3 I)];

b = Nest[{#, a #, a\[Conjugate] #, #} &, 1, 5];

{Re[#], Im[#]} & /@ 
   Accumulate[
    Flatten[{0, a b, a\[Conjugate] b, -b}]] // {\[Rho]\[Chi], # // 
     Line} & // Graphics

NotebookFind[EvaluationNotebook[], "E" <> "xp", Previous];

but I hope there is just another key combination or sth. that I am not aware of.

Edit:

a = Exp[(*1*)1.994 \[Pi]/(3 I)];

b = Nest[{#, a #, a\[Conjugate] #, #} &, (*2*)1, (*3*)5];

{Re[#], Im[#]} & /@ 
   Accumulate[
    Flatten[{0, a b, a\[Conjugate] b, -b}]] // {\[Rho]\[Chi], # // 
     Line} & // Graphics

Do[NotebookFind[EvaluationNotebook[], "(*1*)", Previous], {2}];

is a nice little improvement to my solution as partly suggested by Chris Dengen.

Edit 2:

NotebookFind[EvaluationNotebook[], "(*1*)", EvaluationCell]

This solves:

EvaluationCell is sparsely documented so hard to find in fact I just stumbled upon it. Using the EvaluationCell the search starts from above (eliminating the Do twice construct) as we do not come from an output cell further down the screen.

What remains to be solved:

Note This question is about not losing current position when one presses SHIFT + ENTER inside a Mathematica notebook cell. It is not about content or Manipulate. Sorry for not making that clear at the beginning.

Temporary Note

Now trying the following:

  1. use event handlers to define an alternative evaluation key combination
  2. when triggered, find a way to store the exact keyboard position in the current input cell
  3. evaluate the current input cell
  4. restore the position in the current input cell

I internally hope some function might just take care of the store/restore by chance being optimistic. Being realistic though, I first hope I can even find a way to get at the current keyboard position. Will follow up here if anything materializes out of my attempt.

Upvotes: 14

Views: 1187

Answers (5)

Chris Degnen
Chris Degnen

Reputation: 8655

You can run this cell over and over:

If[NumberQ[x], x++, x = 1];
Print[x]
Do[SelectionMove[EvaluationNotebook[], Previous, Cell], {2}]

This version places the cursor after the Exp in line 1:

a = Exp[1.994 \[Pi]/(3 I)];
b = Nest[{#, a #, a\[Conjugate] #, #} &, 1, 5];
{Re[#], Im[#]} & /@ 
   Accumulate[
    Flatten[{0, a b, a\[Conjugate] b, -b}]] // {# // 
     Line} & // Graphics
Do[NotebookFind[EvaluationNotebook[], "Exp", Previous], {3}];
SelectionMove[EvaluationNotebook[], "Exp", After];

You could also put Evaluate & move on a key combination, e.g. ctrl+r in the example below. This assignment only lasts for the current session but it can be loaded with pre-initialisation so that it is always present. (The key combo item is added to the Insert menu.)

FrontEndExecute[
 FrontEnd`AddMenuCommands[
  "DuplicatePreviousOutput", {Delimiter, 
   MenuItem["Evaluate and return", 
    FrontEnd`KernelExecute[Module[{nb}, nb = SelectedNotebook[];
      SelectionMove[nb, Previous, Cell];
      SelectionMove[nb, Next, Cell];
      SelectionEvaluate[nb];
      Do[SelectionMove[EvaluationNotebook[], Previous, Cell], {2}]]], 
    MenuKey["r", Modifiers -> {"Control"}], 
    System`MenuEvaluator -> Automatic]}]]

To set pre-initialisation save the above code to a package .m file as EvaluteReturn.m in your Documents directory and evaluate the following.

InitializationValue[$PreInitialization] = Hold[Get[
   FileNameJoin[{$HomeDirectory, "Documents", "EvaluateReturn.m"}]]]

To inspect the value

InitializationValue[$PreInitialization]

To clear the value

obj = InitializationObjects[$PreInitialization, {"Local"}]

DeleteObject[obj]

Upvotes: 7

Gregory Klopper
Gregory Klopper

Reputation: 2295

You can use low level notebook programming and a feature called docked cells to add a cell to the top of your notebook which will execute the current cell. This (in theory, haven't tried it) shouldn't take the cursor position out of the cell. to programmatically create the docked cell, create a cell which has the button that does what you want, then execute this code: SetOptions[SelectedNotebook[],"DockedCells"->{Cell[ BoxData[ToBoxes[...your code for execute button...]] , "DockedCell"]}];

I do this all the time with corporate logo as a fixed cell or "Copy as Plain Text"/"Copy as Bitmap" buttons. On notebooks which mess up the kernel heavily, I add buttons for mem management or even restarting the kernel. Just series of shortcuts. You can stack more than one Cell[] object as docked cells.

Upvotes: 2

Brett Champion
Brett Champion

Reputation: 8577

How about using Manipulate? Something like

Manipulate[
 c = a;
 b = Nest[First@f, 1, 
   5]; {Re[#], Im[#]} & /@ 
    Accumulate[
     Flatten[{0, c b, c\[Conjugate] b, -b}]] // {Red, # // Line} & // 
  Graphics, {a, Exp[1.994 \[Pi]/(3 I)], 
  ControlType -> InputField}, {f, 
  HoldForm[{#, c #, c\[Conjugate] #, #} &], ImageSize -> Full, 
  ControlType -> InputField}]

You can just edit the values, and upon hitting enter get a new version of the plot. You can save examples you like by using the '+' button in the top-right corner of the Manipulate to either set bookmarks or paste a snapshot.

enter image description here

Upvotes: 4

Mike Bailey
Mike Bailey

Reputation: 12817

You can use dynamic to make things really nice.

The cell to display results in:

Dynamic[b = Nest[{#, a #, a\[Conjugate] #, #} &, 1, 5];]
Dynamic[{Re[#], Im[#]} & /@ 
    Accumulate[
     Flatten[{0, a b, a\[Conjugate] b, -b}]] // {\[Rho]\[Chi], # // 
      Line} & // Graphics]

The cell to edit in:

k = 1.994;
a = Exp[k \[Pi]/(2 I)];
NotebookFind[EvaluationNotebook[], ToString[k], Previous];

You can then just edit the cell below the display one. It automatically puts you right where you entered your value. If you'd like to make things even easier on yourself you can use Manipulate:

Manipulate[a = Exp[k \[Pi] / (f I)];
 b = Nest[{#, a #, a\[Conjugate] #, #} &, 1, 5];
 {Re[#], Im[#]} & /@ 
    Accumulate[
     Flatten[{0, a b, a\[Conjugate] b, -b}]] // {\[Rho]\[Chi], # // 
      Line} & // Graphics,
 {{k, 1.994}, -3, 3},
 {{f, 3}, -3, 3}]

Upvotes: 2

Dr Joe
Dr Joe

Reputation: 760

There's a function called 'evaluate in place' which allows you to select a section of a cell, and just evaluate that. On the Mac it's command-Enter, instead of control-Enter.

Look at the Evaluate menu, the menu entry should be there along with the bound shortcut key combination.

Upvotes: 1

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