Keeping Observations Based on Conditional Row Numbers

[Yangxi Zhuguan]

Dear Statalist,

Apologies for this rather elementary question. I've dug through the manual and the web but am still in need of a final touch from the community.

So I would like to only keep the 1st, 10th, 19th, ... and 32653rd observation of my data. So the sequence condition is 9x+1 when x progresses from 0 to 3628 by 1. I understand it should be a simple line of command of:

keep if _n = ...

And my question is how can I specify the condition of 9x+1 where x ranges from 0 to 3628 by 1 in order for the keep command to work?

Thank you very much!

Best,
Yangxi Z.

[Clyde Schechter]

keep if mod(_n, 9) == 1 & _n <= 3628*9 + 1

(Note: if the size of your data set is such that there are not 32,662 observations, then the & and everything that follows it can be omitted.)

[Yangxi Zhuguan]

keep if mod(_n, 9) == 1 & _n <= 3628*9 + 1

(Note: if the size of your data set is such that there are not 32,662 observations, then the & and everything that follows it can be omitted.)

Thank you very much!