I have a Stata elapsed date variable (excerpt below) for each patient patid. But I believe I need to generate a new variable if I were to make use of only the year element within that date, that is, not just change the display format.
clear
input long patid float date
1015 18766
1018 13135
1020 13325
1025 14384
1029 14514
1050 13501
1070 14523
1071 14878
1090 14701
1092 14159
end
format %td date
How do I generate a year variable for all dates within the same year? That is all days from 1st January to 31st December of the same year?
That calls for just the function year(), which together with similar stuff is prominently documented at help datetime.
clear
input long patid float date
1015 18766
1018 13135
1020 13325
1025 14384
1029 14514
1050 13501
1070 14523
1071 14878
1090 14701
1092 14159
end
format %td date
gen year = year(date)
list
+--------------------------+
| patid date year |
|--------------------------|
1. | 1015 19may2011 2011 |
2. | 1018 18dec1995 1995 |
3. | 1020 25jun1996 1996 |
4. | 1025 20may1999 1999 |
5. | 1029 27sep1999 1999 |
|--------------------------|
6. | 1050 18dec1996 1996 |
7. | 1070 06oct1999 1999 |
8. | 1071 25sep2000 2000 |
9. | 1090 01apr2000 2000 |
10. | 1092 07oct1998 1998 |
+--------------------------+