Check if rectangles coords intersect with python

Question

I'm training with a website which ask me to make a program which will ask for the coords of two rectangles and check if the rectangles intersect. Then, when I send the program, the website tests it a few times. It asks for the x min, x max, y min and y max of A rectangle and then, B rectangle.

Here's what I do:

xmin_a = int(input()) xmax_a = int(input()) ymin_a = int(input()) ymax_a = int(input()) xmin_b = int(input()) xmax_b = int(input()) ymin_b = int(input()) ymax_b = int(input()) if xmin_a < xmax_b <= xmax_a and (ymin_a < ymax_b <= ymax_a or ymin_a <= ymin_b < ymax_a): print('YES') elif xmin_a <= xmin_b < xmax_a and (ymin_a < ymax_b <= ymax_a or ymin_a <= ymin_b < ymax_a): print('YES') elif xmin_b < xmax_a <= xmax_b and (ymin_b < ymax_a <= ymax_b or ymin_b <= ymin_a < ymax_b): print('YES') elif xmin_b <= xmin_a < xmax_b and (ymin_b < ymax_a <= ymax_b or ymin_b <= ymin_a < ymax_b): print('YES') else: print('NO')

Unfortunately, it doesn't work and I don't get why. Any idea?

PS: http://data.france-ioi.org/Task/7b0ee4fb57949c3db1f694afcef9d1a1//exemple.png

Is this even legal xmin_a < xmax_b <= xmax_a? Did you even check whether the statements you write work like you think they do? — luk32
– luk32, Commented Feb 26, 2014 at 14:17
Yeah it works fine. In fact, the program works sometimes and sometimes not. — user3356177
– user3356177, Commented Feb 26, 2014 at 14:17
Uh, ok, it is quite weird form, at least to me. However, if you say that "It somethimes works" then it is expected to specify the input, actual output and expected output. It is easier to spot the bug if you know the test that fails. — luk32
– luk32, Commented Feb 26, 2014 at 14:21
I am terribly sorry. I normally have my questions filtered by the Java tag. No wonder my answer was downvoted. The syntax is strangely similar, though! (Feel free to throw banana peels at me because Python is in the title of the question) — Rainbolt
– Rainbolt, Commented Feb 26, 2014 at 14:34

M4rtini · Accepted Answer · 2014-02-26 15:32:26Z

I wrote a short program that generates random squares, and tests them with your function. Press control to generate new squares until you see something that fails. I did some quick testing and saw some cases failing. You need to consider if they are counted as intersecting, if they have borders at the exact same value.

like this for example: enter image description here

import numpy as np import matplotlib.pyplot as plt from random import randint def caseTest(xmin_a, xmax_a, ymin_a, ymax_a, xmin_b, xmax_b, ymin_b, ymax_b): if xmin_a < xmax_b <= xmax_a and (ymin_a < ymax_b <= ymax_a or ymin_a <= ymin_b < ymax_a): print('YES'), elif xmin_a <= xmin_b < xmax_a and (ymin_a < ymax_b <= ymax_a or ymin_a <= ymin_b < ymax_a): print('YES'), elif xmin_b < xmax_a <= xmax_b and (ymin_b < ymax_a <= ymax_b or ymin_b <= ymin_a < ymax_b): print('YES'), elif xmin_b <= xmin_a < xmax_b and (ymin_b < ymax_a <= ymax_b or ymin_b <= ymin_a < ymax_b): print('YES'), else: print('NO'), print(xmin_a, xmax_a, ymin_a, ymax_a, xmin_b, xmax_b, ymin_b, ymax_b) def createRandomSquares(): fig = plt.gcf() fig.clf() xmin_a = randint(0, 9) xmax_a = randint(xmin_a + 1, 10) ymin_a = randint(0, 9) ymax_a = randint(ymin_a + 1, 10) xmin_b = randint(0, 9) xmax_b = randint(xmin_b + 1, 10) ymin_b = randint(0, 9) ymax_b = randint(ymin_b + 1, 10) caseTest(xmin_a, xmax_a, ymin_a, ymax_a, xmin_b, xmax_b, ymin_b, ymax_b) sqr1_x = [xmin_a, xmax_a, xmax_a, xmin_a, xmin_a] sqr1_y = [ymin_a, ymin_a, ymax_a, ymax_a, ymin_a] sqr2_x = [xmin_b, xmax_b, xmax_b, xmin_b, xmin_b] sqr2_y = [ymin_b, ymin_b, ymax_b, ymax_b, ymin_b] plt.plot(sqr1_x, sqr1_y) plt.plot(sqr2_x, sqr2_y) ax = plt.gca() ax.set_ylim(min([ymin_b, ymin_a]) - 1, max([ymax_a, ymax_b]) + 1) ax.set_xlim(min([xmin_b, xmin_a]) - 1, max([xmax_a, xmax_b]) + 1) fig.canvas.draw() def key_event(event): if (event.key == 'control'): createRandomSquares() fig = plt.figure() fig.canvas.mpl_connect('key_press_event', key_event) plt.show()

This one gives NO - obviously should be yes.

enter image description here

Are they considered intersecting if one is fully contained in the other?
This one gives YES - i would say that might be NO.

enter image description here

Collectives™ on Stack Overflow

Check if rectangles coords intersect with python

1 Answer 1

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Linked

Related