<>
The calculation of the first dummy "group_d" could, for instance be achieved
without a loop, borrowing ideas from NJC`s FAQ
http://www.stata.com/support/faqs/data/distinctstrings.html (even though
these are not -string-s)
*************
clear*
inp byte(contract_id firm_id) /*
*/ nation_id:mylabel, auto
1 2 "US"
1 2 "US"
4 3 "UK"
4 3 "US"
8 4 "US"
8 4 "UK"
8 3 "US"
9 5 "US"
9 4 "UK"
9 3 "US"
10 5 "US"
10 5 "US"
10 6 "NL"
10 7 "NL"
10 4 "UK"
10 4 "CH"
end
egen groups=group(contract_id /*
*/ firm_id nation_id)
bys contract_id (groups): /*
*/ egen byte distinctcount= /*
*/ total(groups[_n]!=groups[_n+1])
bys contract_id: /*
*/ gen byte group_d = distinctcount!=_N
l, sepby(con) noo
*************
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von joe j
Gesendet: Dienstag, 10. November 2009 16:04
An: [email protected]
Betreff: st: forvalues & replace not working under two 'not equal to'
conditions
My dataset has three variables 1. contract_id, 2. firm_id and 3.
nation_id. I want to create 4 variables, each of which gets a value of
1 if certain conditions are met. The variables I want to create are
specific to the contract id, and are:
1. group_d = 1 when both firm_id and nation_id are same for two or
more firms with the same contract id
2. group_f = 1 when firm_id is same but nation_id is different for
two or more firms with the same contract id
3. nongroup_d = 1 when firm_id is different but nation_id is same for
two or more firms with the same contract id
4 .nongroup_f = 1 when both firm_id and nation_id are different for
two or more firms with the same contract id
The following code works well for the first three variables, but not
for the last, nongroup_f; the value is 1 for all observations. I can't
figure out why.
This is a sample code:
clear
inp str10(contract_id firm_id nation_id)
1 2 "US"
1 2 "US"
4 3 "UK"
4 3 "US"
8 4 "US"
8 4 "UK"
8 3 "US"
9 5 "US"
9 4 "UK"
9 3 "US"
10 5 "US"
10 5 "US"
10 6 "NL"
10 7 "NL"
10 4 "UK"
10 4 "CH"
end
*1.group_d . WORKS!
gen group_d=.
forvalues i=1/`=_N'{
bys contract_id: replace group_d=1 if firm_id==firm_id[_n-`i'] &
nation_id==nation_id[_n-`i']
}
forvalues i=1/`=_N'{
bys contract_id: replace group_d=1 if firm_id==firm_id[_n+`i'] &
nation_id==nation_id[_n+`i']
}
*2.group_f WORKS!
gen group_f=.
forvalues i=1/`=_N'{
bys contract_id: replace group_f=1 if firm_id==firm_id[_n-`i'] &
nation_id!=nation_id[_n-`i']
}
forvalues i=1/`=_N'{
bys contract_id: replace group_f=1 if firm_id==firm_id[_n+`i'] &
nation_id!=nation_id[_n+`i']
}
*3. nongroup_d WORKS!
gen nongroup_d=.
forvalues i=1/`=_N'{
bys contract_id: replace nongroup_d=1 if firm_id!=firm_id[_n-`i'] &
nation_id==nation_id[_n-`i']
}
forvalues i=1/`=_N'{
bys contract_id: replace nongroup_d=1 if firm_id!=firm_id[_n+`i'] &
nation_id==nation_id[_n+`i']
}
*4.nongroup_f DOESN'T WORK!!
gen nongroup_f=.
forvalues i=1/`=_N'{
bys contract_id: replace nongroup_f=1 if (firm_id~=firm_id[_n-`i']) &
(nation_id~=nation_id[_n-`i'])
}
forvalues i=1/`=_N'{
bys contract_id: replace nongroup_f=1 if (firm_id~=firm_id[_n+`i']) &
(nation_id~=nation_id[_n+`i'])
}
*
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*
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