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My data is

data = {{1, 1, 1, 1, 0.469258}, {1, 1, 1, 2, 0.}, {1, 1, 1, 3, -0.000123615}}

On linux-like systems there is a printf routine to make formatted print. How can I use this function from mathematica in order to obtain the formatted text file with 5 columns and 3 rows with a given format.

For instance with printf "%3i %3i %3i %3i %10.6f\n" I am expecting

  1   1   1   1   0.469258
  1   1   1   2   0.000000
  1   1   1   3  -0.000124

Currently I doing

file = "a.dat";
If[FileExistsQ[file], DeleteFile[file]]
cmd = "printf \"%3i %3i %3i %3i %10.6f\\n\"";
Do[
 args = StringRiffle[ToString[#] & /@ s];
 Run[StringRiffle[{cmd, args, ">>", file}]];
 , {s, data}]

But is it an idiomatic method? Will it fail in some cases, like for other variable types or too long strings? Is there a better way?

Improve this question
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  • $\begingroup$ Would Exporting the data as a "Table" (perhaps using appropriate "FieldSeparators" as an option) work for you? $\endgroup$ Commented Feb 27, 2021 at 13:42
  • $\begingroup$ Try: Export["filename", data, "Table"] $\endgroup$ Commented Feb 27, 2021 at 13:50
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    $\begingroup$ @MarcoB With Exporting plus "FieldSeparators" you almost there, but formatting is difficult. I doubt that MA can exactly conform all the rules that printfis using, or am I wrong? I am not after the speed, but more after the control, accuracy and predictability of output. $\endgroup$ Commented Feb 27, 2021 at 14:19
  • 1
    $\begingroup$ Does this answer your question? sprintf() or close equivalent, or re-implementation? $\endgroup$ Commented Feb 28, 2021 at 17:46
  • 1
    $\begingroup$ I cannot write a full answer at this time, but a couple of suggestions: 1) use ToString@*CForm on each argument so that exponentials are written in C syntax instead of Mathematica syntax, 2) if strings are going to be permitted then any characters with special meaning to the shell must be escaped. $\endgroup$ Commented Feb 28, 2021 at 21:00

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