[R] evaluation of the alternative expression in ifelse

[Renaud Lancelot]

Dear all,

I am trying to avoid the warnings produced by:

> x <- -2:2
> log(x)
[1]       NaN       NaN      -Inf 0.0000000 0.6931472
Warning message:
production de NaN in: log(x)

I thought that using ifelse would be a solution, but it is not the case:

> ifelse(test = x < 0, yes = NaN, no = log(x))
[1]       NaN       NaN      -Inf 0.0000000 0.6931472
Warning message:
production de NaN in: log(x)

I am aware of the section "Warning" of the help page for ifelse:
Sometimes it is better to use a construction such as (tmp <- yes;
tmp[!test] <- no[!test]; tmp), possibly extended to handle missing
values in test.

However, is there a way to avoid the evaluation of the alternative
expression in ifelse when the argument test is false ?

Best regards,

Renaud
-- 
Renaud LANCELOT
Département Elevage et Médecine Vétérinaire (EMVT) du CIRAD
Directeur adjoint chargé des affaires scientifiques

CIRAD, Animal Production and Veterinary Medicine Department
Deputy director for scientific affairs

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