[R] How to use ifelse without invoking warnings

[Deepayan Sarkar]

On Sat, Oct 9, 2021 at 3:00 AM Ravi Varadhan via R-help
<r-help using r-project.org> wrote:
>
> Thank you to Bert, Sarah, and John. I did consider suppressing warnings, but I felt that
> there must be a more principled approach.  While John's solution is what I would prefer,
> I cannot help but wonder why `ifelse' was not constructed to avoid this behavior.

Note that John's approach is mentioned twice in the help page for
ifelse, once in the examples, and once quite early on in the "Warning"
section:

     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'.

Best,
-Deepayan

> Thanks & Best regards,
> Ravi
> ________________________________
> From: John Fox <jfox using mcmaster.ca>
> Sent: Thursday, October 7, 2021 2:00 PM
> To: Ravi Varadhan <ravi.varadhan using jhu.edu>
> Cc: R-Help <r-help using r-project.org>
> Subject: Re: [R] How to use ifelse without invoking warnings
>
>
>       External Email - Use Caution
>
>
>
> Dear Ravi,
>
> It's already been suggested that you could disable warnings, but that's
> risky in case there's a warning that you didn't anticipate. Here's a
> different approach:
>
>  > kk <- k[k >= -1 & k <= n]
>  > ans <- numeric(length(k))
>  > ans[k > n] <- 1
>  > ans[k >= -1 & k <= n] <- pbeta(p, kk + 1, n - kk, lower.tail=FALSE)
>  > ans
> [1] 0.000000000 0.006821826 0.254991551 1.000000000
>
> BTW, I don't think that you mentioned that p = 0.3, but that seems
> apparent from the output you showed.
>
> I hope this helps,
>   John
>
> --
> John Fox, Professor Emeritus
> McMaster University
> Hamilton, Ontario, Canada
> web: https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsocialsciences.mcmaster.ca%2Fjfox%2F&data=04%7C01%7Cravi.varadhan%40jhu.edu%7Cfd882e7c4f4349db34e108d989bc6a9f%7C9fa4f438b1e6473b803f86f8aedf0dec%7C0%7C0%7C637692265160038474%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=Q33yXm36BwEVKUWO72CWFpSUx7gcEEXhM3qFi7n78ZM%3D&reserved=0
>
> On 2021-10-07 12:29 p.m., Ravi Varadhan via R-help wrote:
> > Hi,
> > I would like to execute the following vectorized calculation:
> >
> >    ans <- ifelse (k >= -1 & k <= n, pbeta(p, k+1, n-k, lower.tail = FALSE), ifelse (k < -1, 0, 1) )
> >
> > For example:
> >
> >
> >> k <- c(-1.2,-0.5, 1.5, 10.4)
> >> n <- 10
> >> ans <- ifelse (k >= -1 & k <= n, pbeta(p,k+1,n-k,lower.tail=FALSE), ifelse (k < -1, 0, 1) )
> > Warning message:
> > In pbeta(p, k + 1, n - k, lower.tail = FALSE) : NaNs produced
> >> print(ans)
> > [1] 0.000000000 0.006821826 0.254991551 1.000000000
> >
> > The answer is correct.  However, I would like to eliminate the annoying warnings.  Is there a better way to do this?
> >
> > Thank you,
> > Ravi
> >
> >
> >       [[alternative HTML version deleted]]
> >
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> >
>
>
>         [[alternative HTML version deleted]]
>
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