[R] Mean of a row of a data frame

[Richard M. Heiberger]

rowMeans is designed for speed.  It also has as.matrix inside it.

On Tue, Mar 20, 2018 at 10:40 PM, Boris Steipe <boris.steipe at utoronto.ca> wrote:
> R > rowMeans(roop)
> [1] 1.666667 5.333333 3.000000
> R > mean(as.numeric(roop[1,]))
> [1] 1.666667
>
>
> :-)
>
>
>
>
>> On Mar 20, 2018, at 10:18 PM, Sorkin, John <jsorkin at som.umaryland.edu> wrote:
>>
>> I am trying to get the mean of a row of a data frame. My code follows:
>>
>>
>> roop <- data.frame(x=c(1,2,3),y=c(4,5,2),z=c(0,9,4))
>> roop
>> mean(roop[1,])
>> mean(roop[1,c("x","y","z")])
>>
>>
>> I get the following output:
>>
>>> roop
>>  x y z
>> 1 1 4 0
>> 2 2 5 9
>> 3 3 2 4
>>> mean(roop[1,])
>> [1] NA
>> Warning message:
>> In mean.default(roop[1, ]) :
>>  argument is not numeric or logical: returning NA
>>> mean(roop[1,c("x","y","z")])
>> [1] NA
>> Warning message:
>> In mean.default(roop[1, c("x", "y", "z")]) :
>>  argument is not numeric or logical: returning NA
>>
>>
>> It is clear the the mean function does not like the data I am passing to it. I do not know why. How might I correct my code?
>>
>>
>> As always,
>>
>> Thank you,
>>
>> John
>>
>>
>> Thank you,
>>
>> John
>>
>>
>>
>>
>>
>> John David Sorkin M.D., Ph.D.
>> Professor of Medicine
>> Chief, Biostatistics and Informatics
>> University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine
>> Baltimore VA Medical Center
>> 10 North Greene Street
>> GRECC (BT/18/GR)
>> Baltimore, MD 21201-1524
>> (Phone) 410-605-7119
>> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>>
>>
>>       [[alternative HTML version deleted]]
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help at 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.