[R] Conditionally swap two columns of a data.frame?

[Wolski]

Hi!
Better then a cookbook.
http://www.ku.edu/~pauljohn/R/Rtips.html

/E
Ps.


*********** REPLY SEPARATOR  ***********

On 9/16/2004 at 1:55 PM Dan Bolser wrote:

>>>Minter!
>>>
>>>Is there an R cookbook? which lists this kind of common problem and
>>>common
>>>solution?
>>>
>>>
>>>On Thu, 16 Sep 2004, Dimitris Rizopoulos wrote:
>>>
>>>>Hi Dan,
>>>>
>>>>do you need something like that,
>>>>
>>>>dat <- data.frame(V1=rnorm(40000, 10), V2=rnorm(40000, 10))
>>>>ratioV1V2 <- ifelse(dat$V1>dat$V2, dat$V1/dat$V2, dat$V2/dat$V1)
>>>>
>>>>I hope it helps.
>>>>
>>>>Best,
>>>>Dimitris
>>>>
>>>>----
>>>>Dimitris Rizopoulos
>>>>Ph.D. Student
>>>>Biostatistical Centre
>>>>School of Public Health
>>>>Catholic University of Leuven
>>>>
>>>>Address: Kapucijnenvoer 35, Leuven, Belgium
>>>>Tel: +32/16/396887
>>>>Fax: +32/16/337015
>>>>Web: http://www.med.kuleuven.ac.be/biostat/
>>>>     http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm
>>>>
>>>>----- Original Message ----- 
>>>>From: "Dan Bolser" <dmb at mrc-dunn.cam.ac.uk>
>>>>To: <r-help at stat.math.ethz.ch>
>>>>Sent: Thursday, September 16, 2004 2:19 PM
>>>>Subject: [R] Conditionally swap two columns of a data.frame?
>>>>
>>>>
>>>>>
>>>>> I am doing this a kinda dumb way, and it is apparetnly taking
>>>>> forever.
>>>>>
>>>>> I have a data frame with two numeric columns. I want to look at
>>>>their
>>>>> correlation, and I am looking at the size ratio between the two.
>>>>>
>>>>> i.e.
>>>>>
>>>>> plot(density(data$V1/data$V2))
>>>>>
>>>>> This kinda gives me a normal curve showing something about the
>>>>> distribution of the two values.
>>>>>
>>>>> I want to make sure that V1/V2 is always > 1 ...
>>>>>
>>>>> for (i in 1:length(row.names(data)) ){
>>>>>   ratioV1V2 <- if(V1>V2) V1/V2 else V2/V1
>>>>> }
>>>>>
>>>>> This is a bit of a hack, and is taking forever for some reson (about
>>>>> 40,000 rows in my data.frame).
>>>>>
>>>>> I would just like to swap the values in the data frame (to put the
>>>>bigest
>>>>> first for example), then use the above plot to get what I want.
>>>>>
>>>>> Should I use the DB backend to the data to make the dump in this
>>>>way?
>>>>> (involves some hacky sql)
>>>>>
>>>>> Considering I am interested in the range of the ratio between V1 and
>>>>V2,
>>>>> should I be looking at doing a different analysis?
>>>>>
>>>>> I am so dumb, any help is appreciated,
>>>>>
>>>>> Dan.
>>>>>
>>>>> ______________________________________________
>>>>> R-help at stat.math.ethz.ch mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>> PLEASE do read the posting guide!
>>>>http://www.R-project.org/posting-guide.html
>>>>>
>>>>
>>>
>>>______________________________________________
>>>R-help at stat.math.ethz.ch mailing list
>>>https://stat.ethz.ch/mailman/listinfo/r-help
>>>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html



Dipl. bio-chem. Witold Eryk Wolski             @         MPI-Moleculare Genetic   
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