[R] Bug in by() function which works for some FUN argument and does not work for others
Bert Gunter
bgunter.4567 at gmail.com
Fri Apr 15 00:45:33 CEST 2016
You're right, but I think this fails to pinpoint the error. The
problem is that FUN's argument is "applied to (usually data-frame)
subsets of data," and the OP has used FUN = mean, which takes a
vector (+ a few other classes), not a data frame, as argument. See
?mean
Morals:
1. It is rather presumptuous to think that long used, well-tested,
core R functionality like by() have bugs; a (new?) user's first
thought should be to assume it is HIS error, not R's.
2. DO read the Help docs carefully. They are often terse, but usually
they mean what they (appear to) say.
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Thu, Apr 14, 2016 at 2:36 PM, Adrian Dușa <dusa.adrian at unibuc.ro> wrote:
> I think you are not using the best function for what your intentions are.
> Try:
>
>> by(data=mtcars, INDICES=list(as.factor(mtcars$am)), FUN=colMeans)
> : 0
> mpg cyl disp hp drat wt
> qsec vs
> 17.1473684 6.9473684 290.3789474 160.2631579 3.2863158 3.7688947
> 18.1831579 0.3684211
> am gear carb
> 0.0000000 3.2105263 2.7368421
> ---------------------------------------------------------------------------
> : 1
> mpg cyl disp hp drat wt
> qsec vs
> 24.3923077 5.0769231 143.5307692 126.8461538 4.0500000 2.4110000
> 17.3600000 0.5384615
> am gear carb
> 1.0000000 4.3846154 2.9230769
>
> See the difference between colMeans() and mean() in their respective help
> files.
> Hth,
> Adrian
>
> On Thu, Apr 14, 2016 at 11:14 PM, Akhilesh Singh <
> akhileshsingh.igkv at gmail.com> wrote:
>
>> Dear Sirs,
>>
>> I am Professor at Indira Gandhi Krishi Vishwavidyalaya, Raipur,
>> Chhattisgarh, India.
>>
>> While taking classes, I found the *by() *function producing following error
>> when I use FUN=mean or median and some other functions, however,
>> FUN=summary works.
>>
>> Given below is the output of the example I used on a built-in dataset
>> "mtcars", along with error message reproduced herewith:
>>
>> > by(data=mtcars, INDICES=list(mtcars$am), FUN=mean)
>> : 0
>> [1] NA
>> ------------------------------------------------------------
>> : 1
>> [1] NA
>> Warning messages:
>> 1: In mean.default(data[x, , drop = FALSE], ...) :
>> argument is not numeric or logical: returning NA
>> 2: In mean.default(data[x, , drop = FALSE], ...) :
>> argument is not numeric or logical: returning NA
>>
>> However, the same by() function works for FUN=summary, given below is the
>> output:
>>
>> > by(data=mtcars, INDICES=list(mtcars$am), FUN=summary)
>> : 0
>> mpg cyl disp hp
>> Min. :10.40 Min. :4.000 Min. :120.1 Min. : 62.0
>> 1st Qu.:14.95 1st Qu.:6.000 1st Qu.:196.3 1st Qu.:116.5
>> Median :17.30 Median :8.000 Median :275.8 Median :175.0
>> Mean :17.15 Mean :6.947 Mean :290.4 Mean :160.3
>> 3rd Qu.:19.20 3rd Qu.:8.000 3rd Qu.:360.0 3rd Qu.:192.5
>> Max. :24.40 Max. :8.000 Max. :472.0 Max. :245.0
>> drat wt qsec vs am
>>
>> Min. :2.760 Min. :2.465 Min. :15.41 Min. :0.0000 Min. :0
>>
>> 1st Qu.:3.070 1st Qu.:3.438 1st Qu.:17.18 1st Qu.:0.0000 1st Qu.:0
>>
>> Median :3.150 Median :3.520 Median :17.82 Median :0.0000 Median :0
>>
>> Mean :3.286 Mean :3.769 Mean :18.18 Mean :0.3684 Mean :0
>>
>> 3rd Qu.:3.695 3rd Qu.:3.842 3rd Qu.:19.17 3rd Qu.:1.0000 3rd Qu.:0
>>
>> Max. :3.920 Max. :5.424 Max. :22.90 Max. :1.0000 Max. :0
>>
>> gear carb
>> Min. :3.000 Min. :1.000
>> 1st Qu.:3.000 1st Qu.:2.000
>> Median :3.000 Median :3.000
>> Mean :3.211 Mean :2.737
>> 3rd Qu.:3.000 3rd Qu.:4.000
>> Max. :4.000 Max. :4.000
>> ------------------------------------------------------------
>> : 1
>> mpg cyl disp hp drat
>>
>> Min. :15.00 Min. :4.000 Min. : 71.1 Min. : 52.0 Min.
>> :3.54
>> 1st Qu.:21.00 1st Qu.:4.000 1st Qu.: 79.0 1st Qu.: 66.0 1st
>> Qu.:3.85
>> Median :22.80 Median :4.000 Median :120.3 Median :109.0 Median
>> :4.08
>> Mean :24.39 Mean :5.077 Mean :143.5 Mean :126.8 Mean
>> :4.05
>> 3rd Qu.:30.40 3rd Qu.:6.000 3rd Qu.:160.0 3rd Qu.:113.0 3rd
>> Qu.:4.22
>> Max. :33.90 Max. :8.000 Max. :351.0 Max. :335.0 Max.
>> :4.93
>> wt qsec vs am gear
>>
>> Min. :1.513 Min. :14.50 Min. :0.0000 Min. :1 Min. :4.000
>>
>> 1st Qu.:1.935 1st Qu.:16.46 1st Qu.:0.0000 1st Qu.:1 1st Qu.:4.000
>>
>> Median :2.320 Median :17.02 Median :1.0000 Median :1 Median :4.000
>>
>> Mean :2.411 Mean :17.36 Mean :0.5385 Mean :1 Mean :4.385
>>
>> 3rd Qu.:2.780 3rd Qu.:18.61 3rd Qu.:1.0000 3rd Qu.:1 3rd Qu.:5.000
>>
>> Max. :3.570 Max. :19.90 Max. :1.0000 Max. :1 Max. :5.000
>>
>> carb
>> Min. :1.000
>> 1st Qu.:1.000
>> Median :2.000
>> Mean :2.923
>> 3rd Qu.:4.000
>> Max. :8.000
>> >
>>
>> I am using the latest version of *R-3.2.4 on Windows*, however, this error
>> is being generated in the previous version too,
>>
>> Hope this reporting will get serious attention in debugging.
>>
>> With best regards,
>>
>> Dr. A.K. Singh
>> Head, Department of Agril. Statistics
>> Indira Gandhi Krishi Vishwavidyalaya, Raipur
>> Chhattisgarh, India, PIN-492012
>> Mobile: +919752620740
>> Email: akhileshsingh.igkv at gmail.com
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.
>>
>
>
>
> --
> Adrian Dusa
> University of Bucharest
> Romanian Social Data Archive
> Soseaua Panduri nr.90
> 050663 Bucharest sector 5
> Romania
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> 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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