Can't see your data but perhaps:
my_tbl %>%
mutate(Bse_bwt = round(Bse_bwt * 2) / 2) %>%
group_by(Cat, Bse_bwt) %>%
summarize(count = n(),
Bse_ftv = mean(Bse_ftv),
stdev = if_else(count > 1,
sd(Bse_ftv),
NA_real_))
----- Original Message -----
> From: "Jeff Reichman" <reichm...@sbcglobal.net>
> To: r-help@r-project.org
> Sent: Friday, 11 March, 2022 15:14:52
> Subject: [R] stdev error
> r-help forum
>
>
>
> When I run the following code
>
>
>
> my_tbl %>%
>
> mutate(Bse_bwt = round(Bse_bwt * 2) / 2) %>%
>
> group_by(Cat, Bse_bwt) %>%
>
> summarize(count = n(), Bse_ftv = mean(Bse_ftv), stdev = sd(Bse_ftv))
>
>
>
> I get the following error:
>
>
>
> Error: `stdev` refers to a variable created earlier in this summarise().
>
> Do you need an extra mutate() step?
>
>
>
> I suspect it is because the standard deviation of a length-one vector is NA
> and R is errorerrors out on the standard deviation of 1. So then I tried
>
>
>
> summarize(count = n(), Bse_ftv = mean(Bse_ftv), stdev = if(n()>1)
> sd(Bse_ftv) else 0) and this didn't seem to work either. So there has to be
> a way to add some sort of error checker to my standard deviation function to
> check if n > 1 and then take the standard deviation in dplyr.
>
>
>
> Jeff
>
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
--
Chris Evans (he/him) <ch...@psyctc.org>
Visiting Professor, UDLA, Quito, Ecuador & Honorary Professor, University of
Roehampton, London, UK.
Work web site: https://www.psyctc.org/psyctc/
CORE site: https://www.coresystemtrust.org.uk/
Personal site: https://www.psyctc.org/pelerinage2016/
OMbook: https://ombook.psyctc.org/book/
______________________________________________
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