Hi mokuram,
As others have noted, you will profit from a bit more knowledge about
"extraction":
sum(mtcars)
[1] 13942.2
This works because you have "extracted" the first column of the
"mtcars" data frame _as a data frame_
mtcars[1]
mpg
Mazda RX4 21.0
Mazda RX4 Wag
In addition to Petr's remarks:
- why are you doing sum(mtcars)[1]? Do you want the sum of first column of
mtcars? In that case you should do sum(mtcars[,1]).
- similar remarks apply to your use of mean and sd.
Have you read an introduction to R?
Berend
> On 14 Nov 2016, at 04:01, moku...
)
Cheers
Petr
> -Original Message-
> From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of
> moku...@sina.com
> Sent: Monday, November 14, 2016 4:01 AM
> To: r-help
> Subject: [R] question on mean, sum
>
> Hi,
> I am working on functions such as sum(), m
Hi,
I am working on functions such as sum(), mean() ...
> sum(mtcars)[1] 13942.2> mean(mtcars)[1] NAWarning message:In
> mean.default(mtcars) : NA> sd(mtcars)Error in is.data.frame(x) : ()'double'
why got different reply?Is this a BUG for the current version of R?my version
info:version.string
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