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Is there a built-in function which will apply a function f to x when test yields true? A typical usage scenario would be the application of some transformation function depending on the options:

wrapif[Log, mydata, OptionValue["ReturnLogValues"]]

(*instead of*)

If[TrueQ@OptionValue["ReturnLogValues"], Log@mydata, mydata]

It is just a small piece of code to implement, but I need it quite often and wondered why I never found anything built-in. Example implementations:

wrapif[f_, x_, True] := f[x];
wrapif[f_, x_, _] := x;

Or:

wrapif2[f_, x_, test_] := Nest[f, x, Boole[TrueQ@condition]]
Improve this question
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  • $\begingroup$ Another way would be to have "Filter" -> Indentity options and use it like OptionValue["Filter"] @ mydata. No you can easily pass Log there. $\endgroup$
    – Kuba ♦
    Jun 21, 2018 at 12:10
  • $\begingroup$ What about myData // If[..., Log, Identity] $\endgroup$
    – Kuba ♦
    Jun 21, 2018 at 12:55
  • $\begingroup$ wrapif3[f_, x_, test_] := Boole[test] f[x]+(1-Boole[test])x or wrapif4[f_, x_, test_] := {f, Identity}[[2 - Boole[test]]]@x? $\endgroup$
    – kglr
    Jun 21, 2018 at 13:00
  • $\begingroup$ ... wrapif5[f_, x_, test_] := First[RotateRight[{ Identity, f}, Boole[test]]]@x? $\endgroup$
    – kglr
    Jun 21, 2018 at 13:07
  • $\begingroup$ maybe this is not-quite-but-close: GeneralUtilities`MapIf[f_ test_]? $\endgroup$
    – kglr
    Jun 21, 2018 at 13:27

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