Creating a variable length string of whitespaces i

问题:

The following Mathematica function f creates a string of whitespace of length n.

f[n_]:=Fold[StringJoin,"",Array[" "&,n]]

There must be a zillion alternatives to create this function.

How would you have done it?

回答1:

f[n_] := StringJoin @ ConstantArray[" ", n]

Edit: since @ is as idiomatic as @@ and a bit faster (thanks to Mr.Wizard for benchmarking) and shorter i updated the solution.

回答2:

f[n_] := FromCharacterCode[ConstantArray[32, {n}]]

By the way: you should be aware that this type of question is frowned upon in the faq:

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回答3:

f[n_] := StringJoin[Table[" ", {n}]]

回答4:

Spacer and Invisible are also be useful for creating whitespace, with differences in how you specify the size of the space.

回答5:

f = ConstantArray[" ", #] <> "" &;

This is about twice as fast as Thies Heidecke's function, but not nearly as fast as Sjoerd's.

---

For large n a longer initial string is helpful. This is faster than Sjoerd's method for n > 10000:

f2ss = " "~ConstantArray~499 <> "";
f2[n_ /; n < 500] := StringTake[f2ss, n]
f2[n_ /; n < 5000] := StringTake[ConstantArray["          ", ⌈n/10⌉] <> "", n]
f2[n_] := StringTake[ConstantArray[f2@400, ⌈n/400⌉] <> "", n]