Dear Ravi,
On 2021-10-08 8:21 a.m., Ravi Varadhan 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.
The conditional if () else, which works on an individual logical value,
uses lazy evaluation and so can avoid the problem you encountered. My
guess is that implementing lazy evaluation for the vectorized ifelse()
would incur too high a computational overhead for large arguments.
Best,
John
Thanks & Best regards,
Ravi
------------------------------------------------------------------------
*From:* John Fox <j...@mcmaster.ca>
*Sent:* Thursday, October 7, 2021 2:00 PM
*To:* Ravi Varadhan <ravi.varad...@jhu.edu>
*Cc:* R-Help <r-help@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:
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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
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