[R] Efficient swapping

[Anthoni, Peter (IMK)]

how about gdata functions?

set.seed(1)
(tmp <- data.frame(x = 1:10, R1 = sample(LETTERS[1:5], 10, replace = TRUE), R2 = sample(LETTERS[2:6], 10, replace = TRUE)))
tmp.orig=tmp

library(gdata)
bigMap=mapLevels(x=list(factor(tmp[,"R1"]),factor(tmp[,"R2"])),combine = T,codes=FALSE)
mapLevels(tmp[,"R1"]) = bigMap
mapLevels(tmp[,"R2"]) = bigMap
dd=as.integer(tmp[,"R2"])-as.integer(tmp[,"R1"])
odd=dd%%2!=0
swap=tmp[odd,"R2"]
tmp[odd,"R2"]=tmp[odd,"R1"]
tmp[odd,"R1"]=swap

cbind(tmp,odd,tmp.orig)

cheers
Peter



> On 7. Jul 2017, at 00:54, Gang Chen <gangchen6 at gmail.com> wrote:
> 
> Thanks a lot, Ista! I really appreciate it.
> 
> How about a slightly different case as the following:
> 
> set.seed(1)
> (tmp <- data.frame(x = 1:10, R1 = sample(LETTERS[1:5], 10, replace =
> TRUE), R2 = sample(LETTERS[2:6], 10, replace = TRUE)))
> 
>   x R1 R2
>   1  C  B
>   2  B  B
>   3  C  E
>   4  E  C
>   5  E  B
>   6  D  E
>   7  E  E
>   8  D  F
>   9  C  D
>  10  A  E
> 
> Notice that the factor levels between the two factors, R1 and R2,
> slide by one level; that is, factor R1 does not have level F while
> factor R2 does not have level A. I want to swap the factor levels
> based on the combined levels of the two factors as shown below:
> 
> tl <- unique(c(levels(tmp$R1), levels(tmp$R2)))
> for(ii in 1:dim(tmp)[1]) {
>   kk <- which(tl %in% tmp[ii,'R2'], arr.ind = TRUE) - which(tl %in%
>      tmp[ii,'R1'], arr.ind = TRUE)
>   if(kk%%2!=0) { # swap the their levels between the two factors
>      qq <- tmp[ii,]$R1
>      tmp[ii,]$R1 <- tmp[ii,]$R2
>      tmp[ii,]$R2 <- qq
>  }
> }
> 
> How to go about this case? Thanks!
> 
> 
> On Thu, Jul 6, 2017 at 5:16 PM, Ista Zahn <istazahn at gmail.com> wrote:
>> How about
>> 
>> foo <- with(list(r1 = tmp$R1,
>>                 r2 = tmp$R2,
>>                 swapme = (as.numeric(tmp$R1) - as.numeric(tmp$R2)) %% 2 != 0),
>> {
>>    tmp[swapme, "R1"] <- r2[swapme]
>>    tmp[swapme, "R2"] <- r1[swapme]
>>    tmp
>> })
>> 
>> Best,
>> Ista
>> 
>> On Thu, Jul 6, 2017 at 4:06 PM, Gang Chen <gangchen6 at gmail.com> wrote:
>>> Suppose that we have the following dataframe:
>>> 
>>> set.seed(1)
>>> (tmp <- data.frame(x = 1:10, R1 = sample(LETTERS[1:5], 10, replace =
>>> TRUE), R2 = sample(LETTERS[1:5], 10, replace = TRUE)))
>>> 
>>>    x R1 R2
>>> 1   1  B  B
>>> 2   2  B  A
>>> 3   3  C  D
>>> 4   4  E  B
>>> 5   5  B  D
>>> 6   6  E  C
>>> 7   7  E  D
>>> 8   8  D  E
>>> 9   9  D  B
>>> 10 10  A  D
>>> 
>>> I want to do the following: if the difference between the level index
>>> of factor R1 and that of factor R2 is an odd number, the levels of the
>>> two factors need to be switched between them, which can be performed
>>> through the following code:
>>> 
>>> for(ii in 1:dim(tmp)[1]) {
>>>   kk <- which(levels(tmp$R2) %in% tmp[ii,'R2'], arr.ind = TRUE) -
>>> which(levels(tmp$R1) %in% tmp[ii,'R1'], arr.ind = TRUE)
>>>   if(kk%%2!=0) { # swap the their levels between the two factors
>>>      qq <- tmp[ii,]$R1
>>>      tmp[ii,]$R1 <- tmp[ii,]$R2
>>>      tmp[ii,]$R2 <- qq
>>>  }
>>> }
>>> 
>>> More concise and efficient way to do this?
>>> 
>>> Thanks,
>>> Gang
>>> 
>>> ______________________________________________
>>> 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.