R: Reformatting data file -

i have suspect simple data reformatting question. data file (txt) structured observation numbers on separate lines,

1 45 65 78 56 2 89 34 39 55 

the desired output is,

1 45 65 1 78 56 2 89 34 2 39 55 

suggestions on how make conversion appreciated. thanks.

we read file readlines. create index variable , split 'lines'. remove first element of list elements, use read.table read file, , unnest

 lines <- readlines('file.txt')  library(stringr)  #remove leading/lagging spaces if   lines <- str_trim(lines)   #create index mentioned above based on white space   indx  <- !grepl('\\s+', lines)  #cumsum above index create grouping  indx1 <- cumsum(indx)  #split lines , change names of list elements   lst <- setnames(split(lines, indx1), lines[indx])  #use unnest after reading read.table   library(tidyr)  unnest(lapply(lst, function(x) read.table(text=x[-1])), gr)  #   gr v1 v2  #1  1 45 65  #2  1 78 56  #3  2 89 34  #4  2 39 55 

or can use map base r approach

 do.call(rbind,map(cbind, gr=names(lst),               lapply(lst, function(x) read.table(text=x[-1]))))