Compute percentages in a PROC REPORT - sas

Question

PRODUCT CODE Quantity
A 1 100
A 2 150
A 3 50
total product A 300
B 1 10
B 2 15
B 3 5
total product B 30
I made a proc report and the break after product gives me the total quantity for each product. How can I compute an extra column on the right to calculate the percent quantity of product based on the subtotal?

Answer 1

SAS has a good example of this in their documentation, here. I reproduce a portion of this with some additional comments below. See the link for the initial datasets and formats (or create basic ones yourself).
proc report data=test nowd split="~" style(header)=[vjust=b];
format question $myques. answer myyn.;
column question answer,(n pct cum) all;
/* Since n/pct/cum are nested under answer, they are columns 2,3,4 and 5,6,7 */
/* and must be referred to as _c2_ _c3_ etc. rather than by name */
/* in the OP example this may not be the case, if you have no across nesting */
define question / group "Question";
define answer / across "Answer";
define pct / computed "Column~Percent" f=percent8.2;
define cum / computed "Cumulative~Column~Percent" f=percent8.2;
define all / computed "Total number~of answers";
/* Sum total number of ANSWER=0 and ANSWER=1 */
/* Here, _c2_ refers to the 2nd column; den0 and den1 store the sums for those. */
/* compute before would be compute before <variable> if there is a variable to group by */
compute before;
den0 = _c2_;
den1 = _c5_;
endcomp;
/* Calculate percentage */
/* Here you divide the value by its denominator from before */
compute pct;
_c3_ = _c2_ / den0;
_c6_ = _c5_ / den1;
endcomp;
/* This produces a summary total */
compute all;
all = _c2_ + _c5_;
/* Calculate cumulative percent */
temp0 + _c3_;
_c4_ = temp0;
temp1 + _c6_;
_c7_ = temp1;
endcomp;
run;