st: Re: programming advice

["Ed Weil" <ed85@hotmail.co.uk>]

I often get data of this form where x0 corresponds to the value of x1 when 
month = 0 for each set within code1. This needs to be subtracted from x1 to 
get a difference. Due to my lack of programming skills I have to inspect the 
dataset and manually enter the values of x0 for each set of code1. I was 
trying to write a do-file using if constructs to achieve this with no 
success. Could somebody tell me if it is possible to program this and point 
me in the correct direction. The number of results within each "code1" 
varies.
list code1 month x1 x0 in 11/25

    +---------------------------------+
    | code1   month       x1      x0 |
    |---------------------------------|
11. |     6       0    -1.07    -1.07 |
12. |     6       3    -.632    -1.07 |
13. |     7       0    -.292    -.292 |
14. |     7       3    -.595    -.292 |
15. |     8       0    -.269    -.269 |
    |---------------------------------|
16. |     8       3    -.056    -.269 |
17. |     9       0   -1.336   -1.336 |
18. |     9       3     -.83   -1.336 |
19. |     9       9    -.792   -1.336 |
20. |     9      16    -.153   -1.336 |
    |---------------------------------|
21. |    10       0     -.64     -.64 |
22. |    10       3    -.615     -.64 |
23. |    10      16    -.559     -.64 |
24. |    11       0      -.8      -.8 |
25. |    11       3     -.35      -.8 |
    +---------------------------------+
Many thanks,
Ed

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