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contains() fails on intersection between to polygons

See original GitHub issue

Expected behavior and actual behavior.

p1 and p2 are Polygon instances. intr is the intersection between them. p1.contains(intr) should return True but it doesn’t. Same for p2 It seems like the method contains() fails, as the intersection seems to be done properly (visually) Might be some numeric issue but not sure if or how to overcome it.

Steps to reproduce the problem.

p1_coords = \
[[748.8025582487921, 692.7905130423437],
 [758.386063090365, 677.1925344087617],
 [782.1652203101282, 676.7231091250326],
 [788.8580742086473, 683.1149159561049],
 [868.0049913065219, 683.6289962743791],
 [926.8683108501167, 689.7558195905867],
 [945.7907193468513, 708.439577587113],
 [1039.6537221843691, 703.381222940517],
 [1066.324798875523, 680.7152398075801],
 [1133.224871450568, 689.92869220046],
 [1222.5475564764015, 692.7897316662702],
 [1277.5144968118584, 684.5672802321901],
 [1328.0021558805488, 676.1621265825976],
 [1326.815087867148, 619.5785512771574],
 [1299.7103682278287, 615.8195025680548],
 [1295.2342048657717, 591.626525113616],
 [1274.7539157178887, 590.5506388538025],
 [1202.0978166597627, 592.7976585977345],
 [1136.907474756592, 593.9744014790401],
 [1084.7358589468115, 591.2979988449307],
 [1054.321591743031, 608.3179374482914],
 [1047.6196314231581, 601.1199745285347],
 [1034.804148286642, 594.4689776634423],
 [949.9981449369338, 593.7064099888793],
 [940.4460280909863, 595.3257907811172],
 [924.4796508201753, 595.2980651204466],
 [871.9387738363519, 595.6476008591529],
 [810.8642644301572, 596.052802923398],
 [769.0652199778682, 597.2038897158519],
 [720.046350378694, 600.7688245694075],
 [648.8434044602943, 601.2850228232351],
 [642.9491158104589, 607.2758337282743],
 [641.7129825986358, 620.3276349838853],
 [614.2839898484269, 619.8007952616304],
 [616.6784871475897, 693.9077179629917],
 [641.3952794887201, 696.957078173488],
 [647.9645013441202, 706.4594586892523],
 [735.7974745282122, 701.1862915610103]]

p2_coords = \
[[738.4203560383309, 691.7622240616488],
 [748.5093491295943, 676.1691997515779],
 [772.3499404302023, 675.7342536373502],
 [778.8724641068089, 682.1307596677275],
 [852.6315789473684, 654.9473684210527],
 [912.4510044327204, 688.7034730557052],
 [931.9894048538762, 706.3806230658993],
 [1026.4831479732457, 705.8026066911324],
 [1055.555109984319, 680.1104614031487],
 [1121.8072774161926, 689.3606976743876],
 [1211.815557636787, 694.8791651191065],
 [1265.070256365337, 687.6893857680409],
 [1318.132168061228, 672.6966585838568],
 [1319.2148971104832, 619.4745622702778],
 [1297.4406122647656, 616.6996353170073],
 [1281.7452211311079, 589.8756230593528],
 [1261.3858732724157, 591.5322213239801],
 [1190.7847207965747, 592.641429891231],
 [1127.2910885285871, 592.8204989948874],
 [1074.6293839169564, 591.7285619427223],
 [1047.5117346247594, 607.3954488302268],
 [1037.8991398844898, 601.2910510553994],
 [1025.3179858858186, 594.7076173369253],
 [941.4380178004869, 593.7196866948717],
 [931.9447451893386, 595.2893266248864],
 [916.1180159026535, 595.2176239325067],
 [863.9671006403921, 595.4164703212768],
 [803.2269595172519, 595.6469749150042],
 [761.5573616087426, 596.6691028549511],
 [712.5359251472214, 600.0629088525174],
 [641.316892849315, 600.381622070341],
 [635.1911323054353, 606.30835831528],
 [632.654875020185, 617.7509840311711],
 [606.7908837439835, 619.6833511954851],
 [607.9800327681767, 691.4782235311482],
 [633.8669700854907, 695.7953585646385],
 [636.1433061564386, 705.3368220396302],
 [725.0971110529704, 700.1624087171722]]

p1 = Polygon(p1_coords)
p2 = Polygon(p2_coords)

intr = p1.intersection(p2)
print(p1.contains(intr)) # should return True but doesn't
print(p2.contains(intr)) # should return True but doesn't

Operating system

Ubuntu 16.04

Shapely version and provenance

1.6.2.post1 installed from PyPI using pip

Issue Analytics

State:
Created 6 years ago
Comments:5 (2 by maintainers)

Top GitHub Comments

1reaction

yoelkcommented, Feb 2, 2018

Oh, now i get it. Yes, of course. Thanks

On Feb 2, 2018 3:24 PM, “Sean Gillies” notifications@github.com wrote:

@yoelk https://github.com/yoelk sorry, i’m not going to accept the patch because contains works fine, it’s the intersection method that is in error here.

— You are receiving this because you were mentioned.

Reply to this email directly, view it on GitHub https://github.com/Toblerity/Shapely/issues/562#issuecomment-362597290, or mute the thread https://github.com/notifications/unsubscribe-auth/AGTaG4qKNORl6BDnRCJET406o9tAdOlRks5tQxg3gaJpZM4RyNaB .

0reactions

sgilliescommented, Feb 2, 2018

@yoelk sorry, i’m not going to accept the patch because contains works fine, it’s the intersection method that is in error here.

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