[R] Split a data.frame

[jim holtman]

DF = data.frame(name = c('a', 'v', 'c'), val = 0); DF
##   name val
## 1    a   0
## 2    v   0
## 3    c   0
split_str = c('a', 'c')
# If we assume that the values in split_str are ordered in the same order
as in the dataframe, then this might work.

offsets <- match(split_str, DF$name)
# Since you only want the rows in between

DF[diff(offsets), ]
##   name val
## 2    v   0


Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

On Sat, May 19, 2018 at 7:58 AM, Rui Barradas <ruipbarradas using sapo.pt> wrote:

> Hello,
>
> Maybe something like the following.
>
> splitDF <- function(data, col, s){
>     n <- nrow(data)
>     inx <- which(data[[col]] %in% s)
>     lapply(seq_along(inx), function(i){
>         k <- if(inx[i] < n) (inx[i] + 1):(inx[i + 1])
>         data[k, ]
>     })
> }
>
> splitDF(DF, "name", split_str)
>
>
> Hope this helps,
>
> Rui Barradas
>
>
> On 5/19/2018 12:07 PM, Christofer Bogaso wrote:
>
>> Hi,
>>
>> I am struggling to split a data.frame as will below scheme :
>>
>> DF = data.frame(name = c('a', 'v', 'c'), val = 0); DF
>>
>> split_str = c('a', 'c')
>>
>> Now, for each element in split_str, R should find which row of DF contains
>> that element, and return DF with all rows starting from next row of the
>> corresponding element and ending with the preceding value of the next
>> element.
>>
>> So in my case, I should see 2 data.frames
>>
>> 1st data-frame with name = 'v' (i.e. 2nd row of DF)
>>
>> 2nd data.frame with number_of_rows as 0 (as there is no row left after
>> 'c')
>>
>> Similarly if split_str = c('v'') then, my 2 data.frames will be
>>
>> 1st data.frame with name = 'a'
>> 2nd data.frame with name = 'c'
>>
>> Any idea how to efficiently implement above scheme would be highly
>> appreciated. I tried with split() function, however, it is not giving the
>> right answer.
>>
>> Thanks,
>>
>> ______________________________________________
>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>> PLEASE do read the posting guide http://www.R-project.org/posti
>> ng-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
> ______________________________________________
> R-help using 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/posti
> ng-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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