[R] SOLVED: inadverted reordering of a df column when it is copied to another df
karl.schilling at uni-bonn.de
Fri Mar 17 21:39:28 CET 2017
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
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
> 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
>> realized that when I copy column x from data.frame A to B, the order
>> 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
>> PLEASE do read the posting guide
>> and provide commented, minimal, self-contained, reproducible code.
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