Find the largest rectangle of {aspect ratio} that can fit into the given dimensions.

best_fit.py

def get_aspect(width, height):
    """ :return aspect ratio """
    return float(width) / float(height)
    
def get_ideal_size(width, height, ideal_aspect):
    """
    :return the size of the largest rectangle with an aspect
    ratio of 'ideal_aspect' that will fit into width x height.
    """
    aspect = get_aspect(width, height)
    if ideal_aspect < aspect:
        resized = height * ideal_aspect, height
    else:
        resized = width, width / ideal_aspect
    return resized