我有以下变量：
* Example generated by -dataex-. To install: ssc install dataex
clear
input long id int year str20 word
4971 2005 "dividend"
4971 2005 "seed"
4971 2006 "circle"
4971 2008 "shy"
4971 2008 "old"
4971 2009 "stop"
4971 2010 "image"
4971 2010 "mutation"
4971 2011 "coffin"
4971 2011 "commemorate"
4971 2011 "congress"
4971 2011 "publication"
4971 2012 "economics"
4971 2012 "lung"
4971 2013 "pyramid"
4971 2014 "continental"
4971 2015 "environmental"
4971 2015 "battlefield"
4995 2016 "siege"
5051 2007 "confine"
5051 2008 "reject"
5051 2009 "engagement"
5051 2013 "identification"
5051 2013 "root"
5786 2005 "rational"
5786 2008 "jury"
5786 2008 "tidy"
5786 2009 "presence"
5786 2009 "try"
5786 2013 "pocket"
5786 2014 "summary"
5786 2016 "train"
6287 2005 "fish"
6287 2009 "forward"
6287 2011 "prejudice"
6287 2012 "horizon"
6287 2012 "constituency"
6287 2012 "sail"
6287 2012 "assessment"
end
如何在Stata中按年份组合给定ID的所有单词？
例如，对于id == 4971和year == 2011，可以在下面找到预期的输出：
4971 2011 publication coffin commemorate congress publication
答案 0 :(得分：2)
以下对我有用：
bysort id year: generate wanted = word if _n == 1
bysort id year: replace wanted = wanted[_n-1] + " " + word if _n > 1
bysort id year: keep if _n == _N
list id year wanted, sepby(id)
+-------------------------------------------------------+
| id year wanted |
|-------------------------------------------------------|
1. | 4971 2005 dividend seed |
2. | 4971 2006 circle |
3. | 4971 2008 shy old |
4. | 4971 2009 stop |
5. | 4971 2010 image mutation |
6. | 4971 2011 coffin commemorate congress publication |
7. | 4971 2012 economics lung |
8. | 4971 2013 pyramid |
9. | 4971 2014 continental |
10. | 4971 2015 environmental battlefield |
|-------------------------------------------------------|
11. | 4995 2016 siege |
|-------------------------------------------------------|
12. | 5051 2007 confine |
13. | 5051 2008 reject |
14. | 5051 2009 engagement |
15. | 5051 2013 identification root |
|-------------------------------------------------------|
16. | 5786 2005 rational |
17. | 5786 2008 jury tidy |
18. | 5786 2009 presence try |
19. | 5786 2013 pocket |
20. | 5786 2014 summary |
21. | 5786 2016 train |
|-------------------------------------------------------|
22. | 6287 2005 fish |
23. | 6287 2009 forward |
24. | 6287 2011 prejudice |
25. | 6287 2012 horizon constituency sail assessment |
+-------------------------------------------------------+