Question

What would be a pretty way to indent/format the line in the function below? Or should I not be trying to write this as a one liner at all?

def rects_bound(rects):
    """ Returns a rectangle that bounds all given rectangles
    """
    return reduce(lambda (ax,ay,aw,ah), (bx,by,bw,bh): (min(ax,bx),
                                                        min(ay,by),
                                                        max(ax+aw, bx+bw), 
                                                        max(ay+ah, by+bh)), rects)

or maybe

def rects_bound(rects):
    """ Returns a rectangle that bounds all given rectangles
    """
    return reduce(lambda (ax,ay,aw,ah), 
                         (bx,by,bw,bh): (min(ax,bx), min(ay,by),
                                         max(ax+aw, bx+bw), max(ay+ah, by+bh)), 
                  rects)

I usually just kind of “get creative” in these situations, and I know there is probably no “right” way, I’m just interested in your opinions and habits.

Answer 1

If you’re worried about long lines, don’t use a lambda. Use a regular named function instead.

def rects_bound(rects):
    """ Returns a rectangle that bounds all given rectangles
    """
    def bounding_rect_reducer((ax, ay, aw, ah), (bx, by, bw, bh)):
        return (min(ax,bx),
                min(ay,by),
                max(ax+aw, bx+bw), 
                max(ay+ah, by+bh))

    return reduce(bounding_rect_reducer, rects)