怎么将如下形式的数据
type value
a 2
a 5
a 4
a 8
b 9
b 7
b 6
b 5
c 1
c 2
c 7
c 3
按列分类求和后表示成
type value sum
a 2 19
a 5 19
a 4 19
a 8 19
b 9 27
b 7 27
b 6 27
b 5 27
c 1 13
c 2 13
c 7 13
c 3 13
[code:260gpv9y]data test;
input type $ value;
cards;
a 2
a 5
a 4
a 8
b 9
b 7
b 6
b 5
c 1
c 2
c 7
c 3
;
run;
proc sort data=test;
by type;
proc means data=test sum;
var value;by type;
output out=sum sum=sum;
run;
data result (keep=type value sum);
merge test sum;
by type;
run;[/code:260gpv9y]