math - Intersecting rectangles with Python -

given 2 rectangles r1 , r2 try test if 2 intersect. why don't following 2 functions produce same output?

function 1:

def separate_helper(r1, r2):   r1_left, r1_top, r1_right, r1_bottom = r1   r2_left, r2_top, r2_right, r2_bottom = r2    if r1_right < r2_left:     separate = true   elif    r1_left > r2_right:     separate = true   elif r1_top > r2_bottom:     separate = true   elif r1_bottom < r2_top:     separate = true   elif contains(r1, r2):     separate = false   else:     separate = false   return separate 

function 2:

def separate_helper2(r1, r2):   r1_left, r1_top, r1_right, r1_bottom = r1   r2_left, r2_top, r2_right, r2_bottom = r2    separate = r1_right < r2_left or \     r1_left > r2_right or \     r1_top > r2_bottom or \     r1_bottom < r2_top or \     not contains(r1, r2)   return separate 

function check if rectangle 1 contains rectangle 2:

def contains(r1, r2):   r1_left, r1_top, r1_right, r1_bottom = r1   r2_left, r2_top, r2_right, r2_bottom = r2   return r1_right >= r2_right ,  r1_left <= r2_left ,  r1_top <= r2_top ,  r1_bottom >= r2_bottom 

here's test case fails:

assert separate_helper([29, 35, 53, 90], [23, 47, 90, 86]) == separate_helper2([29, 35, 53, 90], [23, 47, 90, 86])

it fails when rectangle 1 contains rectangle 2, can't wrap head around why.

edit:

i'm using quickcheck python , nose test function. here's test code i'm using:

from qc import forall, lists, integers intersect import separate_helper, separate_helper2  @forall(tries=100, r1=lists(items=integers(), size=(4, 4)), r2=lists(items=integers(), size=(4, 4))) def test_separate(r1, r2):   assert separate_helper(r1, r2) == separate_helper2(r1, r2) 

look @ first version:

elif contains(r1, r2):   separate = false else:   separate = false 

assuming through of proper-intersection cases, return false whether r1 contains r2 or not.

but in second version:

... or \ not contains(r1, r2) 

this return false r1 not contain r2, true otherwise.

so, they're doing different things in precisely case "when rectangle 1 contains rectangle 2".

as side question: why should r1 containing r2 return different result r2 containing r1?