Code for companies overlap in a market

[Alex Dong]

Hi,
I'm with the data like follows,

Market	Company	Time
1	A	2009
1	B	2009
1	C	2009
2	B	2009
2	C	2009
2	D	2009
2	E	2009
3	A	2009
3	D	2009
3	E	2009
3	F	2009

Market	Company	Time
1	A	2010
1	B	2010
1	C	2010
1	D	2010
2	B	2010
2	C	2010
2	D	2010
2	E	2010
3	A	2010
3	D	2010
3	E	2010
3	F	2010

1. I was wondering how can I figure out whether both Company B and C are present in a Market or not (may be by generating a dummy).
2. And how to count the Companies show in each Market in different year?

Appreciate any help.

[Øyvind Snilsberg]

bysort Market Time (Company): egen one = max(Company=="B" & Company[_n+1]=="C")
bysort Market Time (Company): gen two = _N

[Alex Dong]

bysort Market Time (Company): egen one = max(Company=="B" & Company[_n+1]=="C")
bysort Market Time (Company): gen two = _N

Thank you Oyvind for your help. I still have a question which is my company B and C is not in ordered.

[Clyde Schechter]

A question very similar to this is asked and answered at https://www.statalist.org/forums/for...te-overlapping, and I believe the answer there, with minimal adaptation, applies here as well.