Paste Mathematica code so that's it's broken into separate input cells

Question

I often copy Mathematica code from websites (such as SO) to a notebook. The code usually gets pasted as a single input cell. I'm looking for a simple way to paste it as several input cells for convenient step-by-step evaluation.

For example,

a = 2;
f[x_] := x^a

Plot[f[x], {x,0,2}]

would ideally paste as two input cells. Manual formatting (i.e. the original newlines) should preferably also be preserved (this is not the case with default pasting).

Generally, if one selects all input cells (ALT-click), copies them into a text editor, then copies the resulting text back into a notebook, one should get a close equivalent of the original cells that were copied.

Collusion

Answer 1

Or.... you can just Hit Ctrl+Shift+D at the point where you'd like to split your singe cell into 2 separate cells. Some times it's advantageous to group multiple operations into a single cell (or rather not split them to begin with). To undo such a split, select both cells (or more than 2 if you'd like) and click Ctrl+Shift+M to merge them into one.

Stereoscopy

@Collusion in that case it's no wonder you asked this question. That would be quite annoying! – Ringler

+1, I did not know about that shortcut, either. I've just lived with it, and assumed there was nothing to be done. – Bayonne

@Collusion yes this is a standard shortcut for dividing and merging. Now what I would like to have is a shortcut for making/unmaking an initialization cell. There is none standard, afaik. Any suggestions? – Marilou

@Marilou While I don't have time to test this now, it should be possible to modify the MenuSetup.tr file (found in SystemFiles/FrontEnd/TextResources/Windows) to add a shortcut key for this item. Make a backup of the file though and make sure the backup doesn't have the .tr extension. – Collusion

@Marilou Alt+C P I is pretty quick for toggling initialisation. – Byword

@Gr3gK1 +1. Thanks for those tips. I didn't know about Ctrl+Shift+M. As regards Cell -> Divide Cell (Ctrl+Shift+D), an insertion point divides the cell in two, but a text selection divides it in three: everything before, the text selection, and everything afterwards. See here (I didn't know about this either until I searched after reading your answer). – Switzerland

@Chris yes, but i was hoping for something simpler. I guess there is no hope – Marilou

Answer 2

This is a simple implementation (I'd also appreciate a code review, I'm not good in front end programming):

(* This converts a sequence of expressions into boxes *)
Clear[makeManyBoxes]
SetAttributes[makeManyBoxes, HoldAllComplete];
makeManyBoxes[e__] := List@ReleaseHold[MakeBoxes /@ HoldComplete[e]]

(* Split a list at separator *)
split[list_, sep_] := 
 DeleteCases[Split[list, #1 =!= sep && #2 =!= sep &], {sep}] 

wr[e_] := NotebookWrite[InputNotebook[], Cell[BoxData[e], "Input"]]

CreatePalette@Button["Paste!",
  Module[{clipboard},
   clipboard = NotebookGet[ClipboardNotebook[]][[1, 1, 1]];
   If[StringQ[clipboard],

    wr /@ 
     split[ToExpression[clipboard, InputForm, makeManyBoxes], "Null"]
    ]
   ]
  ]

It breaks cells at empty lines. For this, we need to parse the expression first (what if an empty line appears in the middle of a long Module?). But parsing alone will cause several problems.

Problems with this implementation:

• it removes comments
• it can't handle incorrect inputs
• it doesn't preserve the formatting (newlines)
• I'm sure there must be several other things that can go wrong

Collusion

Now we need something that can extract a notebook and generate a SO post, interleaving input & output cells, including graphics and commenting out the output cells ... – Indium

@belisarius A good start would be an imgur uploader. imgur[g] should rasterize the argument (to PNG) at an appropriate width for SO, upload it to imgur, and return the markdown ready to be pasted: [mma](http://i.imgur.com/ZENa4.jpg) This should be a good starting point, but I failed at adapting it: https://mcmap.net/q/48186/-upload-to-ifile-it-through-mathematica/695132 EDIT: I think I'll make that a question – Collusion