22

What are best practices for including sections of Mathematica code in posts?

Mathematica differs from many programming languages because many of us use it in "REPL" (read-evaluate-print-line) mode, so output is interspersed with input, making it hard to copy and paste code. Are there any tricks to ameliorate this?

1
  • 3
    Could we make a mode that would accommodate the REPL style of the Mathematica notebook? When you highlight cells and right click, you get a "Copy As" option, could we leverage the options it has in that submenu for display on the site? Commented Jan 17, 2012 at 21:52

4 Answers 4

Reset to default
20

Copying output from Mathematica can be tricky at times. Here are some tips on making it easier:

Copying:

  • Use Copy As -> Plain Text, or Copy As -> Input Text from the context menu to avoid copying (not really human readable) box expressions.

  • If you copy only input cells, the In/Out labels will not be copied. To select all input cells in a notebook, Alt-Click an input cell bracket. (You can copy the relevant section to a new notebook before selecting input cells.)

  • Whenever possible, make sure that the code posted can be copied back to Mathematica and evaluated. But in some special cases it's good to show the formatted expression too, as a screenshot. The image uploader palette makes this very easy.

Unfortunately formatting (indentation and newlines) will get lost when the code is copied. I do not know if there's a good solution for this (I'd be very interested!)

Pasting:

  • When pasting back code to Mathematica, it'll get pasted into a single cell. Cell ->Divide Cell (CTRL-SHIFT-D) is a convenient way to break it into parts again.

A note about In/Out labels:

When I post code to be copied as a whole, I always avoid In/Out labels, as this is inconvenient. But when I'm showing the process of doing something, together with the output, and commenting on each step, I prefer to keep In/Out labels to make it very clear what is the input and what is the output.

2
  • 2
    I use the Code style (Alt/Cmd-8) for input cells. That way, the (manually applied) formatting is retained by copy-and-paste. Commented Jan 22, 2012 at 17:52
  • How about extending the super-unbelievable-image-upload-palette for copying to the clipboard the selected input and output cells and comment out the output ones as in @Sjoerd's answer? Commented Aug 15, 2012 at 7:41
11

I usually edit away any In/Out labels that may be left during copying. I then comment out the output

So 

In[108]:= D[Cos[x] Exp[x], x]

Out[108]= E^x Cos[x] - E^x Sin[x]

becomes:

D[Cos[x] Exp[x], x]

(*  
===> E^x Cos[x] - E^x Sin[x]
*)
8
  • I have not done this before, but I think this is a good pattern to follow! Commented Jan 19, 2012 at 18:08
  • I tried to do this, but I think I'm just too lazy. What about automating it? I'll try to do it eventually, but if anyone can do it now, please implement it and post back! Commented Jan 22, 2012 at 15:15
  • @Szabolcs Perhaps post this as a question? Commented Jan 22, 2012 at 15:24
  • OK, hope people won't get mad at me for a "give me the code" question :-) Commented Jan 22, 2012 at 15:29
  • @Szabolcs It might be interesting. I see two lines of attack: 1) Modify output printing (using $Post or so) or the Output form. 2) At Cell level, modifying cell contents. Commented Jan 22, 2012 at 15:59
  • I would first copy the selection to a new, invisible notebook, then modify the output cells, then copy the whole thing as "plain text", then close the notebook (all of this done programmatically, of course). Commented Jan 22, 2012 at 16:07
  • mathematica.stackexchange.com/questions/484/… Commented Jan 22, 2012 at 16:18
  • @Szabolcs and any graphics in the selection should be uploaded to SE of course ;-) you have done it before... Commented Jan 22, 2012 at 16:19
8

I have taken to using a combination of QUOTE and CODE blocks. That is > followed by five spaces before each line. It's quick to type by hand, and I think it both visually and logically carries the meaning of output.

Range@9

{1, 2, 3, 4, 5, 6, 7, 8, 9}
1
  • 1
    And is easier to hit the shortcut for quote and code than typing (* and *). Heck, I don't even type that thing anymore in Mathematica, as there is Alt-/! Commented May 3, 2012 at 10:20
-5

I find Sjoerd's way of presenting code a bit bloated.

Why not simply use >> for input and << for output?

>> (*If comments are part of the pasted code, there will be no confusion*)
   Print["as to what's a comment and what's code (not that it was such a big problem...)"];

<< "as to what's a comment and what's code (not that it was such a big problem...)"

Because the code block is not executable, since << and >> are Mathematica functions.

4
  • 1
    The whole point of going through the trouble of stripping out the In/Out labels and commenting the output was so that the whole code block can be copied and run in mma without errors. Although I dislike a lot of the other options, they adhere to this important requirement. Yours, complicates things in several ways. In addition to this block being non-executable, >> and << mean specific functions in Mathematica, namely Put and Get. You can see that this is clearly unpopular. I urge you to delete this and remove these from your recent answers where you've been trying to popularize it. Commented Aug 15, 2012 at 16:17
  • I understand. I don't see the urgency to remove this post, though. I've edited it. I'll edit my other answers. Commented Aug 16, 2012 at 23:07
  • 1
    Sorry, I should've just said remove that from your answers. I had "delete this from your answers", which I changed to "remove these from your answers", but forgot to delete the earlier sentence. I can't edit it now to correct it, but please leave this post as is :) Commented Aug 16, 2012 at 23:15
  • No problem, I see that you've already edited the troublesome answer. I'm out of work. Commented Aug 16, 2012 at 23:19

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.