帮忙看一下下面的code啊,各位同学:
data a;
input ID $1. year $4. SBP 3. DBP;
datalines;
1 1950 130 80
1 1950 144 75
1 1951 211 90
2 1950 77 76
2 1951 66 66
3 1952 155 76
3 1952 154 80
3 1950 144 42
3 1951 180 80
2 1951 166 89
;
run;
但是输出地结果是:
The SAS System 20:13 Tuesday, July 2, 2013 1
Obs ID year SBP DBP
1 1 1950 130
2 1 1950 144
3 1 1951 211
4 2 1950 77
5 2 1951 66
6 3 1952 155
7 3 1952 154
8 3 1950 144
9 3 1951 180
10 2 1951 166
ID一列是空的,这是为什么呢????那位能帮我解答一下啊