[R] tibble question with a mean

[Erin Hodgess]

David
That's awesome!

Thank you!!!

Erin Hodgess, PhD
mailto: erinm.hodgess using gmail.com


On Thu, Sep 20, 2018 at 9:19 PM David L Carlson <dcarlson using tamu.edu> wrote:

> > xt[, 2:3] %>% colMeans
>          y          z
>  2.5000000 -0.4401625
>
> > xt[2] %>% colMeans
>   y
> 2.5
> > t(xt[, 2]) %>% mean
> [1] 2.5
>
> -------------------------
> David L. Carlson
> Department of Anthropology
> Texas A&M University
>
> -----Original Message-----
> From: R-help [mailto:r-help-bounces using r-project.org] On Behalf Of Peter
> Langfelder
> Sent: Thursday, September 20, 2018 8:08 PM
> To: Erin Hodgess <erinm.hodgess using gmail.com>
> Cc: r-help <r-help using r-project.org>
> Subject: Re: [R] tibble question with a mean
>
> I don't know tibble, so I'll do the same with a plain data frame:
>
> a =
>
> data.frame(x=LETTERS[1:4],y=1:4,z=rnorm(4),a=c("dog","cat","tree","ferret"))
> > a
>   x y           z      a
> 1 A 1 -0.08264865    dog
> 2 B 2  0.32344426    cat
> 3 C 3 -0.80416061   tree
> 4 D 4  1.27052529 ferret
> > mean(a[2:3])
> [1] NA
> Warning message:
> In mean.default(a[2:3]) : argument is not numeric or logical: returning NA
> > mean(as.matrix(a[2:3]))
> [1] 1.338395
>
> The reason you get an error on mean(a[2:3]) is that a[2:3] is still a data
> frame (a special list) and you cannot simply apply mean to a list. You need
> to first convert to a matrix or vector which can then be fed to mean().
>
> Peter
>
>
> On Thu, Sep 20, 2018 at 5:50 PM Erin Hodgess <erinm.hodgess using gmail.com>
> wrote:
>
> > Hello!
> >
> > Here is a toy tibble problem:
> >
> > xt <-
> > tibble(x=LETTERS[1:4],y=1:4,z=rnorm(4),a=c("dog","cat","tree","ferret"))
> > str(xt)
> > Classes ‘tbl_df’, ‘tbl’ and 'data.frame': 4 obs. of  4 variables:
> >  $ x: chr  "A" "B" "C" "D"
> >  $ y: int  1 2 3 4
> >  $ z: num  0.3246 0.0504 0.339 0.4872
> >  $ a: chr  "dog" "cat" "tree" "ferret"
> > #No surprise
> >  xt %>% mean
> > [1] NA
> > Warning message:
> > In mean.default(.) : argument is not numeric or logical: returning NA
> > #surprised!
> > mean(xt[2:3])
> > [1] NA
> > Warning message:
> > In mean.default(xt[2:3]) : argument is not numeric or logical: returning
> NA
> >  xt[, 2:3] %>% mean
> > [1] NA
> > Warning message:
> > In mean.default(.) : argument is not numeric or logical: returning NA
> >
> > I have a feeling that I'm doing something silly wrong.  Has anyone run
> into
> > this, please?  I saw something like this on this list, but didn't see a
> > solution.
> >
> > Thanks,
> > Erin
> >
> >
> > Erin Hodgess, PhD
> > mailto: erinm.hodgess using gmail.com
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > and provide commented, minimal, self-contained, reproducible code.
> >
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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