Here is a test of the different proposed solutions and a new one faster.
In conclusion, ifelse much be used with caution:
Aini = runif(100, min=-1,max=1)
library(microbenchmark)
A <- Aini
microbenchmark({B1 <- ifelse( A < 0, sqrt(-A), A )})
# mean = 77.1
A <- Aini
microbenchmark({B2 <-
or even simpler
sqrt(abs(A))
On Mon, Dec 9, 2019 at 8:45 AM Eric Berger wrote:
>
> Hi Bob,
> You wrote "the following error message" -
> when in fact it is a Warning and not an error message. I think your
> code does what you hoped it would do, in the sense it successfully
> calculates the
Hi Bob,
You wrote "the following error message" -
when in fact it is a Warning and not an error message. I think your
code does what you hoped it would do, in the sense it successfully
calculates the sqrt(abs(negativeNumber)), where appropriate.
If you want to run the code without seeing this
The sqrt(-A) is evaluated for all A. The result returned is conditional on the
first argument but the other two arguments are evaluated on the entire vector.
Kevin
--
Kevin E. Thorpe
Head of Biostatistics, Applied Health Research Centre (AHRC)
Li Ka Shing Knowledge Institute of St. Michael's
Please consider the following two R statements:
A = runif(20, min=-1,max=1)
ifelse( A < 0, sqrt(-A), A )
The second statement produces the following error message:
rt(-A) : NaNs produced
I understand that you cannot take the square root of a negative number
but I thought the
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