R: Grouping the Index's of Rows

Question

I am working with the R programming language. I made the following dataset:

Startx = rnorm(600,10,2)
Starty = rnorm(600,7,1)
Endx = rnorm(600,2,2)
Endy = rnorm(600,5,1)

Lines <- data.frame(Startx, Starty, Endx, Endy)

Here is how the dataset looks like:

> head(Lines)

     Startx   Starty      Endx     Endy
1  6.139012 8.238896 1.5970315 5.314411
2 11.079151 7.478156 4.2811267 6.940548
3  8.189728 6.622191 0.4567519 5.067486
4 11.424529 6.440073 1.5545516 6.044430
5  9.291668 6.122416 0.4611325 4.927958
6 11.218345 6.382152 2.7499929 5.006792

Next, I added an "index" (ID) variable to each row:

library(dplyr)
Lines <- mutate(Lines, id = rownames(Lines))

> head(Lines)

     Startx   Starty      Endx     Endy id
1  6.139012 8.238896 1.5970315 5.314411  1
2 11.079151 7.478156 4.2811267 6.940548  2
3  8.189728 6.622191 0.4567519 5.067486  3
4 11.424529 6.440073 1.5545516 6.044430  4
5  9.291668 6.122416 0.4611325 4.927958  5
6 11.218345 6.382152 2.7499929 5.006792  6

Question: Now, I am trying to "ID's" of these rows, so that :

the ID for the first 6 rows is "1"
the ID for the next 6 rows is "2"
the ID for the next 6 rows is "3"
etc.

Something that looks like this:

      Startx   Starty       Endx     Endy id
1   6.139012 8.238896  1.5970315 5.314411  1
2  11.079151 7.478156  4.2811267 6.940548  1
3   8.189728 6.622191  0.4567519 5.067486  1
4  11.424529 6.440073  1.5545516 6.044430  1
5   9.291668 6.122416  0.4611325 4.927958  1
6  11.218345 6.382152  2.7499929 5.006792  1
7   7.574718 6.750851  2.9556587 5.417020  2
8  13.182436 7.376812  2.1243483 6.620904  2
9  10.332929 9.083481  1.2771253 4.216452  2
10  3.706943 7.758393 -1.7933726 4.751453 2
11 10.676039 6.350639  1.5230948 5.316503 2
12 14.895981 8.130952  4.3009821 5.072671 2
13 13.329396 5.631068  0.5448433 3.770325 3
14 13.452864 5.988059  5.8843498 4.877926 3
15  8.036621 5.826816  3.2609650 5.686083 3
16 11.792844 6.977793  1.5243847 4.820037 3
17 14.178991 5.165727  5.0643746 5.088643 3
18 10.905152 8.426026  4.5867895 3.670802 3
19  8.867147 7.731436  1.4050062 4.546500 4
20 11.559410 8.094610  3.2317544 4.203140 4

What I tried so far: At the moment, I was able to temporarily solve this problem by brining this data frame into Microsoft Excel and semi-manually accomplish this task. But I was hoping that there might be a somewhat more "efficient" way to do this in R.

Can someone please show me how to do this?

Thanks

user_13321647 · Answer

library(dplyr)
Lines <- mutate(Lines, id = rownames(Lines)) %>% 
mutate(ID = rep(row_number(), each=6, length.out = n()))

    Startx   Starty        Endx     Endy  id ID
1    6.791532 6.344849  0.56099835 4.557484   1  1
2    9.907718 6.333883 -0.36249572 5.159065   2  1
3   10.073533 6.031520 -0.37077947 5.124256   3  1
4    6.407786 8.020749  5.66129797 2.063402   4  1
5   11.736735 6.926289  7.19877205 3.880176   5  1
6   10.699439 7.250388  0.63691737 4.748458   6  1
7   10.387614 6.240162  3.53096881 3.154894   7  2
8    9.126212 6.463472  3.45527039 3.536357   8  2
9    9.875189 7.486275  3.00520682 4.750458   9  2
10   8.157215 5.853551  0.88678342 4.222574  10  2
11  10.122712 7.491003 -0.05283184 3.311954  11  2
12  11.169240 6.113054 -1.32465120 4.879334  12  2
13   8.611155 6.974169  2.84887239 4.545410  13  3
14  10.275210 7.497898  0.47346846 4.332957  14  3
15   8.940241 6.014243  3.84548597 4.413747  15  3
16  13.440112 7.125526  1.28334553 6.691715  16  3
17   8.521694 5.439896  1.34850499 5.281371  17  3
18   9.169292 6.692165  2.83474345 3.654708  18  3
19   6.358885 5.968021  3.45486083 4.647540  19  4
20  11.072854 7.416212  1.98031674 6.080660  20  4
21  12.855619 5.905539  3.01461705 5.800007  21  4
...

Update for OP:

Lines %>% 
    as_tibble() %>% 
    mutate(id = row_number(),
           ID = rep(row_number(), each=6, length.out = n()))

user_3732271 · Answer

We can use

library(dplyr)
Lines <- Lines %>%
          mutate(id = as.integer(gl(n(), 6, n())))

R: Grouping the Index's of Rows

2 Answers