Create index column based on existent groups of ro

The question is similar to (Update) Add index column to data.frame based on two columns

Here my example data.frame:

df = read.table(text = 'ID  Day Count   Count_group 
77661   14498   4   5
76552   14498   4   5
37008   14498   4   5
34008   14498   4   5
30004   14497   1   5
30004   14497   1   4   
28047   14496   3   4   
28049   14496   3   4   
29003   14496   3   4   
69012   14468   1   4   
69007   14467   3   4   
69012   14467   3   4   
69020   14467   3   4   
42003   13896   2   4   
42011   13896   2   4   
22001   13895   2   4   
23007   13895   2   4   
28047   14496   3   3   
28049   14496   3   3   
29003   14496   3   3   
69007   14467   3   3   
69012   14467   3   3   
69020   14467   3   3   
48005   14271   2   2   
48007   14271   2   2   
22001   13895   2   2   
23007   13895   2   2   
47011   14320   1   2   
73005   14319   1   2   
73005   14319   1   1', header = TRUE)

The Count col shows the sum of the ID values grouped by Day. The Count_group shows the sum of the unique Count vales grouped by Day and Day -1.

I need to create an index column which groups the Count_group by Day and Day -1 following the descending order of the df (with duplicates!).

Here my expected output:

ID     Day  Count Count_group index_col
77661   14498   4   5           1
76552   14498   4   5           1
37008   14498   4   5           1
34008   14498   4   5           1
30004   14497   1   5           1
30004   14497   1   4           2
28047   14496   3   4           2
28049   14496   3   4           2
29003   14496   3   4           2
69012   14468   1   4           3
69007   14467   3   4           3
69012   14467   3   4           3
69020   14467   3   4           3
42003   13896   2   4           4
42011   13896   2   4           4
22001   13895   2   4           4
23007   13895   2   4           4
28047   14496   3   3           5
28049   14496   3   3           5
29003   14496   3   3           5
69007   14467   3   3           6
69012   14467   3   3           6
69020   14467   3   3           6
48005   14271   2   2           7
48007   14271   2   2           7
22001   13895   2   2           8
23007   13895   2   2           8
47011   14320   1   2           9
73005   14319   1   2           9
73005   14319   1   1          10

And do the same but with index_col grouping by 3 days: Day, Day -1 and Day -2:

    df_2 = read.table(text = 'ID Day Count Count_group
30004   14497   1   5
28047   14496   3   5
28049   14496   3   5
29003   14496   3   5
69012   14495   1   5
69007   14467   3   5
69012   14467   3   5
69020   14467   3   5
42003   14466   1   5
42011   14465   1   5
28047   14496   3   4
28049   14496   3   4
29003   14496   3   4
69012   14995   1   4
22001   13895   2   4
23007   13895   2   4
28047   13894   2   4
28049   13894   2   4
42003   14466   1   2
42011   14465   1   2
28047   13894   2   2
28049   13894   2   2
69012   14995   1   1
42011   14465   1   1', header = TRUE)

Expected output:

ID     Day  Count Count_group index_col
30004   14497   1   5           1
28047   14496   3   5           1
28049   14496   3   5           1
29003   14496   3   5           1
69012   14495   1   5           1
69007   14467   3   5           2
69012   14467   3   5           2
69020   14467   3   5           2
42003   14466   1   5           2
42011   14465   1   5           2
28047   14496   3   4           3
28049   14496   3   4           3
29003   14496   3   4           3
69012   14995   1   4           3
22001   13895   2   4           4
23007   13895   2   4           4
28047   13894   2   4           4
28049   13894   2   4           4
42003   14466   1   2           5
42011   14465   1   2           5
28047   13894   2   2           6
28049   13894   2   2           6
69012   14995   1   1           7
42011   14465   1   1           8

Do you have any suggestion? I desire to create a generic code that could be applied (with a few adjustments) to both df, df_2 and to other data.frames with grouping variable of n days.

Using dplyr:

df %>% mutate(index_col = cumsum(!c(+Inf,diff(Day))%in%c(0,-1)))

Explanation:

 c(+Inf,diff(Day))

As you want two consecutive days, I compute the difference on the Day with diff(Day). As diff return vector of size n-1, I have to add a value for the top of the vector, I choose +Inf.

!(... %in% c(0,-1))

I test that the value is the same Day or Day-1 as they must be grouped, I want when it's not the case.

cumsum(...)

Finally, I use cumsum to know how many of change occur.

The output:

It's work for your two exemples

> df %>% mutate(index_col = cumsum(!c(+Inf,diff(Day))%in%c(0,-1)))

      ID   Day Count Count_group index_col
1  30004 14497     1           4         1
2  28047 14496     3           4         1
3  28049 14496     3           4         1
4  29003 14496     3           4         1
5  69012 14468     1           4         2
6  69007 14467     3           4         2
7  69012 14467     3           4         2
8  69020 14467     3           4         2
9  42003 13896     2           4         3
10 42011 13896     2           4         3
11 22001 13895     2           4         3
12 23007 13895     2           4         3
13 28047 14496     3           3         4
14 28049 14496     3           3         4
15 29003 14496     3           3         4
16 69007 14467     3           3         5
17 69012 14467     3           3         5
18 69020 14467     3           3         5
19 48005 14271     2           2         6
20 48007 14271     2           2         6
21 22001 13895     2           2         7
22 23007 13895     2           2         7
23 47011 14320     1           2         8
24 73005 14319     1           2         8
25 73005 14319     1           1         8

and

> df_2 %>% mutate(index_col = cumsum(!c(+Inf,diff(Day))%in%c(0,-1)))

      ID   Day Count Count_group index_col
1  30004 14497     1           5         1
2  28047 14496     3           5         1
3  28049 14496     3           5         1
4  29003 14496     3           5         1
5  69012 14495     1           5         1
6  69007 14467     3           5         2
7  69012 14467     3           5         2
8  69020 14467     3           5         2
9  42003 14466     1           5         2
10 42011 14465     1           5         2
11 28047 14496     3           4         3
12 28049 14496     3           4         3
13 29003 14496     3           4         3
14 69012 14495     1           4         3
15 22001 13895     2           4         4
16 23007 13895     2           4         4
17 28047 13894     2           4         4
18 28049 13894     2           4         4
19 42003 14466     1           2         5
20 42011 14465     1           2         5
21 28047 13894     2           2         6
22 28049 13894     2           2         6
23 69012 14995     1           1         7
24 42011 14465     1           1         8