Sequence Function with By Option

[Mahmut Coskun]

Hi Everybody,

I have a data set as follows with reference and date values. I wanna group every 20 reference numbers and create a variable with respect to their group as I made below for a group of 3 reference numbers to create a group variable.
As far as I understand, I have to use seq with by option. I tried it but the results didn't appear as I wanted.

ref I date I group
1 2011 1
1 2012 1
1 2013 1
1 2014 1
1 2015 1
1 2016 1
2 2012 1
2 2013 1
2 2014 1
7 2012 1
7 2013 1
7 2014 1
8 2012 2
12 2014 2
12 2015 2
12 2016 2
12 2017 2
14 2014 2
14 2015 2
14 2016 2
14 2017 2

Thanks in advance,
Mahmut

[Nick Cox]

The command seq is community-contributed but was superseded by the egen function seq() — itself long since adopted as official. It is not clear why you want a sequence variable that ignores your identifier and date variables but the block() option allows blocks of 20 (your text), 12 (your example), and so forth.

[Mahmut Coskun]

Thank you for your answer, Nick. It's my fault I couldn't explain properly. Actually, in my example, I am not grouping 12 observations, I am grouping 3 different ref (1,2,7)-(8,12,14) regardless of the number of observations for each ref. In my real data, I will group 20 different refs together for each group regardless of the number of observations.