Sorting the data set

[Jenna Kerry]

Hello!

Currently, I am working with Stata 18.0. My data looks like,

* Example generated by -dataex-. For more info, type help dataex
clear
input float(ID event year Event_year)
1    . 2001 2002
1 2002 2002 2002
1    . 2003 2002
1    . 2004 2002
1    . 2005 2002
1    . 2006 2002
1    . 2007 2002
2    . 2001 2005
2    . 2002 2005
2    . 2003 2005
2    . 2004 2005
2 2005 2005 2005
2    . 2006 2005
2    . 2007 2005
3    . 2001 2003
3    . 2002 2003
3 2003 2003 2003
3    . 2004 2003
3    . 2005 2003
3    . 2006 2003
3    . 2007 2003
4    . 2001    .
4    . 2002    .
4    . 2003    .
4    . 2004    .
4    . 2005    .
4    . 2006    .
4    . 2007    .
end

Now, here, an event occurs at a different period for every ID, listed under the variable event. I want to create a variable Event_year, which will list the event period for every year. That is, I want to get the following result:

* Example generated by -dataex-. For more info, type help dataex
clear
input float(ID event year Event_year)
1    . 2001 2002
1 2002 2002 2002
1    . 2003 2002
1    . 2004 2002
1    . 2005 2002
1    . 2006 2002
1    . 2007 2002
2    . 2001 2005
2    . 2002 2005
2    . 2003 2005
2    . 2004 2005
2 2005 2005 2005
2    . 2006 2005
2    . 2007 2005
3    . 2001 2003
3    . 2002 2003
3 2003 2003 2003
3    . 2004 2003
3    . 2005 2003
3    . 2006 2003
3    . 2007 2003
4    . 2001    .
4    . 2002    .
4    . 2003    .
4    . 2004    .
4    . 2005    .
4    . 2006    .
4    . 2007    .
end

Could anyone please help me with the code here?

Thank you so much!

[daniel klein]

One event per ID?

sort ID event
by ID (event) : generate int Event_year = event[1]

[Jenna Kerry]

Dear daniel klein,

Yes, thank you so much for the code. It worked!

Meanwhile, I applied the following code.

bys ID (event): gen wanted= event[1]

Could you please tell me how this code is different from yours? Or do they work in the same way?

Thank you so much!

[daniel klein]

Your code stores wanted as a float (or double, depending on your settings), mine stores Event_year as an int. Otherwise, there is no difference. I have recently started to prefer

sort ...
by ...

over

bys ...

because I find the former makes it more explicit that the data are sorted.

[Jenna Kerry]

I got it! Thank you!