``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36``` ```* The LAG function works only with a constant. * The following syntax produce the lagged values which equal LAG(y,lgx) where lgx is a variable whose value varies for each case. * Raynald Levesque rlevesque@videotron.ca (solution no 1 was posted to usenet on 2000/06/26). DATA LIST FREE / LGX Y. BEGIN DATA 1 5 2 6 1 4 3 3 1 2 3 5 2 3 1 3 3 2 2 2 3 4 2 5 1 6 3 7 2 5 1 4 3 3 2 3 1 6 3 7 2 5 3 3 2 5 1 3 3 2 2 1 3 6 2 8 2 7 2 5 2 3 2 9 END DATA. SAVE OUTFILE='c:\\temp\\mydata.sav'. **********************. *** SOLUTION no 1: this assumes we DO know the max value of lgx. **********************. DO REPEAT cnt=1 TO 20. IF lgx=cnt lagg=lag(y,cnt). END REPEAT. EXE. **********************. *** SOLUTION no 2: this is a solution when we DO NOT know the min and max values of lgx. **********************. GET FILE='c:\\temp\\mydata.sav'. COMPUTE dummy=1. AGGREGATE /OUTFILE=* /BREAK=dummy /lagmin = MIN(lgx) /lagmax = MAX(lgx). WRITE OUTFILE='c:\\temp\\temp.sps' /'DO REPEAT cnt='lagmin' TO 'lagmax'.' /'IF lgx=cnt lagg=lag(y,cnt).' /'END REPEAT.'. EXECUTE. GET FILE='c:\\temp\\mydata.sav'. INCLUDE FILE='c:\\temp\\temp.sps'. EXECUTE. ```
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