sprintf() or close equivalent, or re-implementation?

Question

Is there a sprintf() command (some command that takes a printf-style format string and a list of values to insert into the string) or something very much like it (preferably with a similar style of format specifiers)? Or, alternately, how would I implement sprintf() in Mathematica?

Answer 1

I've had a need for such a function several times, and I found this implementation of C-style *printf functions, by Vlad Seghete. To use it, all you need to do is extract the files to $UserBaseDirectory/MathPrintF/ and you're all set.

Here's an example once you've installed it:

<<MathPrintF`
sprintf["%d %s %d %s, %s %s %s %s", 
    Sequence @@ Riffle[{1, 2, "red", "blue"}, {"fish"}, {2, -1, 2}]]

Out[1]= 1 fish 2 fish, red fish blue fish

---

Also note the following caveat in the README

Limited Functionality

While we tried to mimic the C-standard as much as possible, only certain features are implemented. These are mainly dictated by what we needed at the time. In particular %d, %f, %e, %E and %s with most of their options are implemented.

Answer 2

Not as such. The closest equivalent is StringForm, but it doesn't provide the formatting options that the printf family does. StringForm gets a lot of use in the creation of messages.

Example:

StringForm["The value of Pi is ``", NumberForm[N[Pi], 3]]

(* ==>  "The value of Pi is 3.14" *)

Note that StringForm does not create a string, it merely displays with a special formatting. It can easily be converted to the equivalent string using ToString@StringForm[...] though.

Answer 3

Mathematica does not have a built-in equivalent to sprintf. The closest thing is StringForm which allows placeholders within a string to be replaced, but does not perform any formatting of the replacement values:

sprintf[control_, args___] := StringForm[control, args] // ToString

sprintf["hello, ``", "Joe"]
(* "hello, Joe" *)

It is not pretty, but we could use JLink to access Java's printf-like formatting syntax:

Needs["JLink`"]
LoadJavaClass["java.lang.String"];
LoadJavaClass["java.lang.reflect.Array"];
jsprintf[control_, args___] :=
  JavaBlock @ Module[{jArgs, array}
  , jArgs = MakeJavaObject @ N @ # & /@ {args}
  ; array = JavaNew["[Ljava.lang.Object;", Length@jArgs]
  ; MapIndexed[java`lang`reflect`Array`set[array, #2[[1]]-1, #1]&, jArgs]
  ; java`lang`String`format[control, array]
  ]

jsprintf["Hello, %s: Pi is %16.14f", "Joe", Pi]
(* "Hello, Joe: Pi is 3.14159265358979" *)

Answer 4

The simple (e.g. non-tabular, no-formatting) case would look something like this.

mmaSprintf[s : {__String}, d_?VectorQ] /; Length[d] == Length[s] := 
 StringJoin[Riffle[Riffle[s, ToString /@ d], " "]]

Message has a syntax similar to sprintf() but not the formatting capabilities. From the documentation:

rsqrt::nnarg = "The argument `1` is not greater than or equal to zero.";
Message[rsqrt::nnarg, x]