You may have purchased the pattern to make the pineapple robe... it has been pretty popular which is pretty awesome - it's my favorite too!
So say you don't want to invest ALL that time and ALL that yarn... Make a shorter version!
Repeat the pattern for the body pieces 3 times total on the back piece, once to establish the collar for each of the front pieces, and then 2 repeats of the normal pattern after that, and two repeats of the pattern for the sleeves. Now you have a nice short summer sweater instead of a robe! YAY! Stitch happy!