Create Sequence of Repeated Values, in Sequence

Create sequence of repeated values, in sequence?

You missed the each= argument to rep():

R> n <- 3
R> rep(1:5, each=n)
 [1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5
R>

so your example can be done with a simple

R> rep(1:8, each=20)

How to create a sequence column for repeated values?

data$sequence <- unlist(lapply( with(data, rle(count)$lengths), seq_len))
data
   ID count sequence
1    1     2        1
1.1  1     2        2
2    2     4        1
2.1  2     4        2
2.2  2     4        3
2.3  2     4        4
3    3     6        1
3.1  3     6        2
3.2  3     6        3
3.3  3     6        4
3.4  3     6        5
3.5  3     6        6
4    4    10        1
4.1  4    10        2
4.2  4    10        3
4.3  4    10        4
4.4  4    10        5
4.5  4    10        6
4.6  4    10        7
4.7  4    10        8
4.8  4    10        9
4.9  4    10       10

Sequence with repeating numbers

Another option

library(dplyr)
df %>%
   mutate(pair = as.integer(gl(n(), 2, n())))
#    id color pair
#1   1   red    1
#2   2   red    1
#3   3   red    2
#4   4   red    2
#5   5   red    3
#6   6  blue    3
#7   7  blue    4
#8   8  blue    4
#9   9  blue    5
#10 10  blue    5

Or with rep and cumsum

df %>% 
    mutate(pair = cumsum(rep(c(TRUE, FALSE), length.out = n())))

Or much simpler case with base R

df$pair <- c(TRUE, FALSE)
df$pair <- cumsum(df$pair)

Repeating a repeated sequence

You can do it with a single rep call. The each and times parameters are evaluated sequentially with the each being done first.

rep(1:4, times=3, each=3)  # 'each' done first regardless of order of named parameters
#[1] 1 1 1 2 2 2 3 3 3 4 4 4 1 1 1 2 2 2 3 3 3 4 4 4 1 1 1 2 2 2 3 3 3 4 4 4

How to generate repeating numbers in sequence

Hierarchical query might help to produce result you posted:

SQL> with
  2  c1 as
  3    (select lpad(1 + level - 1, 2, '0') col1
  4     from dual
  5     connect by level <= 12
  6    ),
  7  c2 as
  8    (select lpad(1 + level - 1, 2, '0') col2
  9     from dual
 10     connect by level <= 5
 11    )
 12  select c1.col1, c2.col2
 13  from c1 cross join c2
 14  order by c1.col1, c2.col2;

CO CO
-- --
01 01
01 02
01 03
01 04
01 05
02 01
02 02
02 03
02 04
02 05
03 01
03 02
<snip>
11 04
11 05
12 01
12 02
12 03
12 04
12 05

60 rows selected.

SQL>

Oracle: create sequence number for repeated rows

select id, value, row_number() over (partition by value order by id) as seq
from your_table;