[R] 'Split' character

[Dimitris Rizopoulos]

one way is the following:

vals <- do.call(paste, c(mydata[1:2], sep = ":"))
fc <- factor(vals, levels = unique(vals))
mydata.split <- split(mydata, fc, drop = TRUE)
names(mydata.split)


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
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      http://www.student.kuleuven.be/~m0390867/dimitris.htm


Quoting Sébastien <pomchip at free.fr>:

> One additionnal question about a problem that I just noticed in my script:
> the list created by my split function is sorted in the increasing order
> and not in the current order of the elements of the do.call argument
> (see the results of the two last lines of the following script). I was
> unsuccesful in tweaking my split function to have a proper order...
> If there is no way to do that, I guess it comes down to a very basic
> question: how can I reorder a list ?
>
> ####
> how can I reorder the list 'mydata.split' according to
>
> a<-rep(1.5:10.5,each=2)
> b<-rep(21:30,each=2)
> cd<-101:120
> mydata<-data.frame(a,b,cd)
>
> mydata.split <- split(mydata,do.call(paste,c(mydata[,1:2],sep =
> ":")),drop=TRUE)
> names(mydata.split)
> unique(do.call(paste,c(mydata[,1:2],sep = ":")))
>
> ####
>
> Sebastien
>
> Gabor Grothendieck a écrit :
>> Try this using the BOD data frame that comes with R or
>> try using interaction in place of paste:
>>
>> split(BOD, do.call(paste, c(BOD, sep = ":")), drop=TRUE)
>>
>>
>> On Nov 25, 2007 10:23 AM,  <pomchip at free.fr> wrote:
>>
>>> Thanks Jim and Herinque for you reply.
>>>
>>> The substitution you are both proposing works fine, except when a   
>>> or b contains
>>> decimal numbers (which is mostly my case in a real dataset). In   
>>> this case, there
>>> is no distinction between the decimal point and the one introduced  
>>>  by the split
>>> function.
>>> If the split function cannot be customized, then I guess I have to first
>>> substitute the decimal point in my dataset by e.g. a * sign and   
>>> change it back
>>> to a . when the split is done...
>>>
>>> Sebastien
>>>
>>> jim holtman a écrit :
>>>
>>>
>>>> Here is one way:
>>>>
>>>>
>>>>> a<-1:10
>>>>> b<-21:30
>>>>> mydata<-data.frame(a,b)
>>>>> mydata.split<-split(mydata,(mydata[,1:2]),drop=TRUE)
>>>>> x <- mydata.split
>>>>> # customize the names
>>>>> names(x) <- sapply(strsplit(names(x), "\\."), paste, collapse="-my
>>>>>
>>> character-")
>>>
>>>>> x
>>>>>
>>>> $`1-my character-21`
>>>>   a  b
>>>> 1 1 21
>>>>
>>>> $`2-my character-22`
>>>>   a  b
>>>> 2 2 22
>>>>
>>>> $`3-my character-23`
>>>>   a  b
>>>> 3 3 23
>>>> ...........
>>>>
>>>> On Nov 24, 2007 6:15 PM,  <pomchip at free.fr> wrote:
>>>>
>>>>> Dear R-users,
>>>>>
>>>>> The following code splits a very simple dataframe into a list,   
>>>>> each element
>>>>>
>>> of
>>>
>>>>> the list being one line of the dataframe. You will see that the split
>>>>>
>>> function
>>>
>>>>> names each element of the list by using uses the content of a and b and
>>>>>
>>> merging
>>>
>>>>> them with a "." character. Is there a way to customize this character?
>>>>>
>>>>> a<-1:10
>>>>> b<-21:30
>>>>> mydata<-data.frame(a,b)
>>>>> mydata.split<-split(mydata,(mydata[,1:2]),drop=TRUE)
>>>>> mydata.split
>>>>>
>>>>> Thanks in advance for your help.
>>>>>
>>>>> Sebastien
>>>>>
>>>>> ______________________________________________
>>>>> R-help at r-project.org mailing list
>>>>> 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
>>> 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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>
>



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