It's the sequential nature of the process that's getting you.
Try doing it all at once:
replace team=31
replace team = cond(sub_out == 1, team[_n - 1] - 2^(player - 1), ///
cond(sub_in == 1, team[_n - 1] + 2^(player - 1), ///
team[_n-1])) if _n>1
Tom
-----------------------------------
Thomas J. Steichen
[email protected]
-----------------------------------
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Eric G. Wruck
Sent: Thursday, January 08, 2009 11:45 AM
To: [email protected]
Subject: st: Handling Play-by-Play Basketball Data
I am trying to analyze basketball data for my favorite team, the
Davidson Wildcats. In particular, I want to see how the team
performs with a given line-up on the floor. Here is an example of
the data:
+--------------------------------------------------------+
| clock davidson player |
|--------------------------------------------------------|
10. | 18:19 0 |
11. | 18:19 0 |
12. | 18:05 REBOUND (OFF) by BARR, Bryant 1 |
13. | 18:05 MISSED JUMPER by PAULHUS GOSSELIN,Max 3 |
14. | 18:01 MISSED LAYUP by ROSSITER, Steve 5 |
|--------------------------------------------------------|
15. | 17:57 REBOUND (DEF) by BARR, Bryant 1 |
16. | 17:44 MISSED JUMPER by LOVEDALE, Andrew 4 |
17. | 17:42 SUB OUT: ROSSITER, Steve 5 |
18. | 17:42 SUB IN : ALLISON, Ben 7 |
19. | 17:42 FOUL by ROSSITER, Steve (P1T1) 5 |
|--------------------------------------------------------|
20. | 17:29 FOUL by LOVEDALE, Andrew (P1T2) 4 |
+--------------------------------------------------------+
I want to create a variable team whose value will tell me who is on
the floor at any one time. I do this by assigning values to the
players & by summing the 2^(player - 1) for the players on the floor;
I want the variable team to contain this sum. The starting players
I've numbered 1 through 5 so that the initial team value is 31 = 2^(1
- 1) + 2^(2 - 1) + 2 ^(3 - 1) + 2^(4 - 1) + 2^(5 - 1). So what I
want to do is subtract 2^(player - 1) from team for that player taken
out & then immediately adding 2^(player - 1) for the player coming
in. I then need to retain this new value until there is another
substitution. Here's the code I am using:
gen team = 1 + 2 + 4 + 8 + 16
replace team = team[_n - 1] - 2^(player - 1) if sub_out == 1
replace team = team[_n - 1] + 2^(player - 1) if sub_in == 1
replace team = team[_n - 1] if sub_out ~= 1 & sub_in ~= 1 & _n > 1
However, I get this in the way of results:
+-------------------------------------------------------+
| davidson player team |
|-------------------------------------------------------|
10. | 0 31 |
11. | 0 31 |
12. | REBOUND (OFF) by BARR, Bryant 1 31 |
13. | MISSED JUMPER by PAULHUS GOSSELIN,Max 3 31 |
14. | MISSED LAYUP by ROSSITER, Steve 5 31 |
|-------------------------------------------------------|
15. | REBOUND (DEF) by BARR, Bryant 1 31 |
16. | MISSED JUMPER by LOVEDALE, Andrew 4 31 |
17. | SUB OUT: ROSSITER, Steve 5 15 |
18. | SUB IN : ALLISON, Ben 7 79 |
19. | FOUL by ROSSITER, Steve (P1T1) 5 79 |
|-------------------------------------------------------|
20. | FOUL by LOVEDALE, Andrew (P1T2) 4 79 |
21. | 0 79 |
22. | STEAL by LOVEDALE, Andrew 4 79 |
23. | TURNOVR by BARR, Bryant 1 79 |
24. | 0 79 |
|-------------------------------------------------------|
25. | 0 79 |
26. | REBOUND (DEF) by LOVEDALE, Andrew 4 79 |
27. | MISSED 3 PTR by BARR, Bryant 1 79 |
28. | REBOUND (DEF) by LOVEDALE, Andrew 4 79 |
29. | ASSIST by CURRY, Stephen 2 79 |
|-------------------------------------------------------|
30. | GOOD! LAYUP by ALLISON, Ben [PNT] 7 79 |
31. | REBOUND (DEF) by CURRY, Stephen 2 79 |
32. | TURNOVR by LOVEDALE, Andrew 4 79 |
33. | SUB OUT: BARR, Bryant 1 30 |
34. | SUB OUT: CURRY, Stephen 2 28 |
|-------------------------------------------------------|
35. | SUB IN : ARCHAMBAULT, Will 6 60 |
36. | SUB IN : MCKILLOP, Brendan 8 188 |
37. | 0 188 |
38. | SUB OUT: LOVEDALE, Andrew 4 23 |
39. | SUB OUT: PAULHUS GOSSELIN,Max 3 19 |
|-------------------------------------------------------|
40. | SUB IN : CURRY, Stephen 2 21 |
+-------------------------------------------------------+
This is actually what I want until I get to line 33 when Barr leaves
the court. I want team to be 79 - 2^(1 - 1) = 78 at that point.
When Curry comes on, I want team to be 78 + 2^(2 - 1) = 80. Instead
the calculation is made relative to the initial value for team of 31.
How do I fix this?
Many thanks,
Eric
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