generating a new variable that takes on the value of another variable if a third variable matches a value

[Thijs de Jong]

Hello, i want to generate a new variable called "td" that takes on the value of the variable target if rank is 1 when dup is 1 and the value of the variable target if rank is 2 when dup is 2. the first table is the data that i have right now and the second table is the data that i want to have with the new variable. please let me know what i can do!

Company_id	target	rank	dup
1	.	.	1
1	.	.	1
1	3	1	1
1	.	.	1
1	5	2	1
1	.	.	1
1	7	3	1
1	.	.	2
1	.	.	2
1	3	1	2
1	.	.	2
1	5	2	2
1	.	.	2
1	7	3	2
1	.	.	3
1	.	.	3
1	3	1	3
1	.	.	3
1	5	2	3
1	.	.	3
1	7	3	3

Company_id	target	rank	dup.	td.
1	.	.	1	3
1	.	.	1	3
1	3	1	1	3
1	.	.	1	3
1	5	2	1	3
1	.	.	1	3
1	7	3	1	3
1	.	.	2	5
1	.	.	2	5
1	3	1	2	5
1	.	.	2	5
1	5	2	2	5
1	.	.	2	5
1	7	3	2	5
1	.	.	3	7
1	.	.	3	7
1	3	1	3	7
1	.	.	3	7
1	5	2	3	7
1	.	.	3	7
1	7	3	3	7

[Nick Cox]

Your wording and your example don't seem to match. Your wording to me implies

gen td = target if (rank == 1 & dup == 1) | (rank == 2 & dup == 2)

[Thijs de Jong]

Hey Nick Cox , thanks for your reaction! when i use this code i only get the value 3 when dup is 1 when target is equal to three but i need it to be 3 on every row where dup is 1. I can't seem to find what i need to change to get it done?

this is the output that i get when i use your code:

Company_id	target	rank	dup	td
1	.	.	1	.
1	.	.	1	.
1	3	1	1	3
1	.	.	1	.
1	5	2	1	.
1	.	.	1	.
1	7	3	1	.
1	.	.	2	.
1	.	.	2	.
1	3	1	2	.
1	.	.	2	.
1	5	2	2	5
1	.	.	2	.
1	7	3	2	.
1	.	.	3	.
1	.	.	3	.
1	3	1	3	.
1	.	.	3	.
1	5	2	3	.
1	.	.	3	.
1	7	3	3	7

but i need the output to be like the second table in my original post

[Nick Cox]

Guessing wildly

gen td = target if (rank == 1 & dup == 1) | (rank == 2 & dup == 2)

bysort id (td) : replace td = td[1]