how to computer the mean average precision ?

[andyqian2015]

Hi,I try to drop the net resolution to raise the fps. and then I use the MPII Human Pose Dataset mentioned in your article to check out how much the map drop.On the Website:
http://human-pose.mpi-inf.mpg.de/#evaluation I mess around by the README.

pos = zeros(length(rect),2);
for ridx = 1:length(rect)
    pos(ridx,:) = [rect(ridx).objpos.x rect(ridx).objpos.y];
end
x1 = min(pos(:,1)); y1 = min(pos(:,2)); x2 = max(pos(:,1)); y2 = max(pos(:,2));

where can I get the rect ?

load('groups_v12.mat','groups');
[imgidxs_multi_test,rectidxs_multi_test] = getMultiPersonGroups(groups,RELEASE,false);

what is the groups_v12.mat ?
I search on the web for a day, and get little effective information. can you give me some suggestion ? thx