主要目的是为了之后生成一对countrypair在2000-2008年存不存在争端的dummyvariable
startyear和endyear代表在如观测1，2002-2005年都有持续争端

clear
input long caseid int(startyear endyear sendercountry) str3 sendercountry_abb str32 sendercountry_name int targetstate str3 targetstate_abb str32 targetstate_name
1 2002 2005    2 "USA" "United States of America" 731 "PRK" "North Korea"
1 2002 2005  740 "JPN" "Japan"                    731 "PRK" "North Korea"
2 2002 2004  732 "ROK" "South Korea"              731 "PRK" "North Korea"
2 2002 2004  900 "AUL" "Australia"                731 "PRK" "North Korea"

end


想把数据改写为如下形式【不知道如何简单的改写，目前的想法有点繁琐...】
如observation 1:
1 2002 2 "USA" "United States of America" 731 "PRK" "North Korea"
1 2003 2 "USA" "United States of America" 731 "PRK" "North Korea"
1 2004 2 "USA" "United States of America" 731 "PRK" "North Korea"
1 2005 2 "USA" "United States of America" 731 "PRK" "North Korea"
【以下都ok】
并对所有observation生成新的变量dummy=1
与year（1列数据，2000-2008）合并，for dummy=. assign value = 0

望赐教！