R help - Mar 2017 - inadverted reordering of a df column when it is copied to another df

Dear all:

I have two data.frames A and B of the same number of rows (about 
40,000). I realized that when I copy column x from data.frame A to B, 
the order of this column  gets changed. This seems to affect only values 
in rownumbers > ~ 35/36,000. It also happens in any of the following 
three approaches:

A$x <- B$x

x <- B$x (here, x is still in the correct order)
B$x <- x : now x is reordered

B <- cbind(A, B$x)

I am working with Windows7Pro/64bit, R 3.3.3, and RStudio 0.99.903.

Any help would be appreciated.

Best regards

Karl Schilling

Dear Karl,

This is hard to investigate without a reproducible example.

Best regards,
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium

To call in the statistician after the experiment is done may be no
more than asking him to perform a post-mortem examination: he may be
able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does
not ensure that a reasonable answer can be extracted from a given body
of data. ~ John Tukey


2017-03-17 16:05 GMT+01:00 Karl Schilling <karl.schilling at
uni-bonn.de>:
> Dear all:
>
> I have two data.frames A and B of the same number of rows (about 40,000). I
> realized that when I copy column x from data.frame A to B, the order of
this
> column  gets changed. This seems to affect only values in rownumbers > ~
> 35/36,000. It also happens in any of the following three approaches:
>
> A$x <- B$x
>
> x <- B$x (here, x is still in the correct order)
> B$x <- x : now x is reordered
>
> B <- cbind(A, B$x)
>
> I am working with Windows7Pro/64bit, R 3.3.3, and RStudio 0.99.903.
>
> Any help would be appreciated.
>
> Best regards
>
> Karl Schilling
>
> ______________________________________________
> 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.

You are wrong. No reordering occurs.

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 Fri, Mar 17, 2017 at 8:05 AM, Karl Schilling
<karl.schilling at uni-bonn.de> wrote:
> Dear all:
>
> I have two data.frames A and B of the same number of rows (about 40,000). I
> realized that when I copy column x from data.frame A to B, the order of
this
> column  gets changed. This seems to affect only values in rownumbers > ~
> 35/36,000. It also happens in any of the following three approaches:
>
> A$x <- B$x
>
> x <- B$x (here, x is still in the correct order)
> B$x <- x : now x is reordered
>
> B <- cbind(A, B$x)
>
> I am working with Windows7Pro/64bit, R 3.3.3, and RStudio 0.99.903.
>
> Any help would be appreciated.
>
> Best regards
>
> Karl Schilling
>
> ______________________________________________
> 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.

Reprex confirming Bert:

A <- data.frame( y = 1L:40000L )
B <- data.frame( x = 1L:40000L )
A$x <- B$x
plot(B$x)

#' ![](http://i.imgur.com/cXSFsBh.png)

Care to demonstrate for us, Karl?

https://cran.r-project.org/web/packages/reprex/README.html

On Fri, 17 Mar 2017, Bert Gunter wrote:
> You are wrong. No reordering occurs.
>
> 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 Fri, Mar 17, 2017 at 8:05 AM, Karl Schilling
> <karl.schilling at uni-bonn.de> wrote:
>> Dear all:
>>
>> I have two data.frames A and B of the same number of rows (about
40,000). I
>> realized that when I copy column x from data.frame A to B, the order of
this
>> column  gets changed. This seems to affect only values in rownumbers
> ~
>> 35/36,000. It also happens in any of the following three approaches:
>>
>> A$x <- B$x
>>
>> x <- B$x (here, x is still in the correct order)
>> B$x <- x : now x is reordered
>>
>> B <- cbind(A, B$x)
>>
>> I am working with Windows7Pro/64bit, R 3.3.3, and RStudio 0.99.903.
>>
>> Any help would be appreciated.
>>
>> Best regards
>>
>> Karl Schilling
>>
>> ______________________________________________
>> 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.
>
> ______________________________________________
> 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.
>
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Dear All:

it seems I have solved my reordering issue, and to thank all those who 
answered, I briefly list the mistake I made.

I stared out from some data.frame holding values x and a grouping 
factor. Actually, my factor was a number (but not numeric) which was, 
however, not ordered. So it would go something like 1 1 1 2 2 2 4 4 4 3 3 3.

Then I performed some calculation on subsets of x defined by this factor 
using by(x, factor, function).

I then converted the result from the list obtained to a data.frame, and 
from this data.frame I copied one column into my original data.frame. 
The point I apparently missed was that the list obtained using "by",
was
ordered based on the factor (i.e. 1,1,1,2,2,2,3,3,3,4,4,4), and the same 
was true for the df I generated from this list.

Thank you for all your input

Karl



On 17.03.2017 16:16, Thierry Onkelinx wrote:
 > Dear Karl,
 >
 > This is hard to investigate without a reproducible example.
 >
 > Best regards,
 > ir. Thierry Onkelinx
 > Instituut voor natuur- en bosonderzoek / Research Institute for Nature
 > and Forest
 > team Biometrie & Kwaliteitszorg / team Biometrics & Quality
Assurance
 > Kliniekstraat 25
 > 1070 Anderlecht
 > Belgium
 >
 > To call in the statistician after the experiment is done may be no
 > more than asking him to perform a post-mortem examination: he may be
 > able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher
 > The plural of anecdote is not data. ~ Roger Brinner
 > The combination of some data and an aching desire for an answer does
 > not ensure that a reasonable answer can be extracted from a given body
 > of data. ~ John Tukey
 >
 >
 > 2017-03-17 16:05 GMT+01:00 Karl Schilling <karl.schilling at
uni-bonn.de>:
 >> Dear all:
 >>
 >> I have two data.frames A and B of the same number of rows (about 
40,000). I
 >> realized that when I copy column x from data.frame A to B, the order 
of this
 >> column  gets changed. This seems to affect only values in rownumbers
> ~
 >> 35/36,000. It also happens in any of the following three approaches:
 >>
 >> A$x <- B$x
 >>
 >> x <- B$x (here, x is still in the correct order)
 >> B$x <- x : now x is reordered
 >>
 >> B <- cbind(A, B$x)
 >>
 >> I am working with Windows7Pro/64bit, R 3.3.3, and RStudio 0.99.903.
 >>
 >> Any help would be appreciated.
 >>
 >> Best regards
 >>
 >> Karl Schilling
 >>
 >> ______________________________________________
 >> 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.


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