Merge columns of coordinates and construct sequence I have to following data frame.

    x1     x2          x3
    0   58.33546    15.14554
    0   58.33604    15.14571
    0   58.33645    15.14581
    0   58.33681    15.14591
    0   58.33722    15.14600
    0   58.33810    15.14604
    0   58.33900    15.14599
    0   58.33966    15.14578


Consisting of long and lat, each pair belongs to a string (0,1,3,4 and so on, only the string 0 is displayed above).

I would like to first construct a new column with the pairs (x2,x3). How do I do that?

The coordinates above corresponding to 0 is actually a journey (say X), if there is another journey (Y) whose first coordinate is the same as X last, I would like to merge the sequence X and Y coordinates together and call that journey X (the continuation of X simply).

My data set is called data, for some reason merging them together wont work with 

data[, x4 := paste(data$x2, data$x3)]


This will create a new column, only isplaying x2.
it probably depends on the use of your new generated column. Here I try to reproduce your example: 

x1 &lt;- c(0, 0)
x2 &lt;- c(58.33546, 58.33604)
x3 &lt;- c(15.14554, 15.14571)
df &lt;- data.frame(x1, x2, x3)
df$x4 &lt;- paste("(", as.character(df$x2), ", ", as.character(df$x3), ")")


And df$x4 will look like:

[1] "( 58.33546 ,  15.14554 )" "( 58.33604 ,  15.14571 )"


If you want to show the coordinates, the above format should be fine. If you want to do further analysis with that column, some other transformations are required.