[R] sd in aggregate and help.search/?? seem not to work as usual in latest version

[Jim Lemon]

Hi Marvin,
One way to get around the problem with "sd" is to only process those
columns of a data frame for which the variance is defined. It is an
opportunity to show students how  to write wrapper functions as well:

sd_num<-function(x) return(ifelse(is.numeric(x),sd(x),NA))
df<-data.frame(group=rep(0:1,each=5),value=1:10,name=LETTERS[1:10])
aggregate(df[,2:3],by=df[1],FUN="sd_num")

Jim

On Tue, Jul 2, 2019 at 3:47 AM Marvin Kiene <maki using maki-science.org> wrote:
>
> Hello dear helpers,
>
> I am currently running a small R-crash course for beginners at my
> university, since I believe that there a far too few lectures about how to
> use R.
>
> Thereby, I showed the '??' or 'help.search()' function to the students as
> well as the 'aggregate()' function with 'FUN=sd'.
>
>
>
> The code worked fine for me - as usual (in version 3.5.1) - but not for the
> students. Doing some research got me to the point, that in the current
> version (3.6.0),
>
> 'aggregate' cannot use 'sd' for data.frames with mixed columns of factors
> and numeric columns and throws an error (which is somewhat ok, since 'var()'
> is not applicable for factors, of course)  instead of putting 'NA's into the
> respective columns like it does with 'FUN=mean' and like it does in the
> former version(s).
>
> Is this a bug or a feature? It would be nice to work with it, the way I am
> used to. Of course it is not difficult to work around this problem, but it
> is somewhat strange, why it was changed that way (if this was intended).
>
>
>
> Additionally, the 'help.search()' always just gives the result: "No results
> found", for all of my students.
>
>
>
> I didn't find any post about that issues so far, so I am not sure whether
> this are known issues (but all of my 10 students had this problem).
>
>
>
> If this were intended changes, I would be interested, what the reason is and
> whether there are direct workarounds (e.g. instead of using only numeric
> columns), for those issues.
>
> Otherwise I am looking forward to a fixed version.
>
>
>
> Thanks in advance for your help!
>
>
>
> Kind regards,
>
> Marvin Kiene
>
>
>
> Doctoral Student
>
> Department of Animal Ecology I, AG Prof. Laforsch
>
> University of Bayreuth
>
> 95440 Bayreuth
>
> Germany
>
>
>
>
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>
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