yep, that's a good example of what I refer to as IKEA assembling your groupby. You need to put something like 3 parts together before it does what you want, and

yep, that's a good example of what I refer to as IKEA assembling your groupby. You need to put something like 3 parts together before it does what you want, and they aren't that intuitive (or they only are in retrospect).