[postgis-users] st_equals on line with tolerance

[Hugues François]

Hi, 

Maybe you could have a look at the snaptogrid function to address this kind of precision issue. 

select st_equals(st_snaptogrid(a.geom,51),st_snaptogrid(b.geom,51)) 
from 
(select st_geomfromtext('LINESTRING(571927 6327619.2,571906.899999999 6327612.4,571826.700000003 6327586.3,571770.600000001 6327567,571718.700000003 6327549.9,571670.899999999 6327532.4,571589.5 6327505)') geom) a, 
(select st_geomfromtext('LINESTRING(571927 6327619.2,571906.899999999 6327612.4,571826.700000003 6327586.3,571824.343590402 6327585.48932789,571770.600000001 6327567,571718.700000003 6327549.9,571670.899999999 6327532.4,571589.5 6327505)') geom) b 

Cheers, 
Hug 







De: "GUILLAUME ARNAUD" <guillaume.arnaud at ledepartement82.fr> 
À: "PostGIS Users Discussion" <postgis-users at lists.osgeo.org> 
Envoyé: Jeudi 5 Décembre 2019 14:56:46 
Objet: [postgis-users] st_equals on line with tolerance 



Hi, 

I need to compare these 2 lines (srid : 2154) : 


"LINESTRING(571927 6327619.2,571906.899999999 6327612.4,571826.700000003 6327586.3,571770.600000001 6327567,571718.700000003 6327549.9,571670.899999999 6327532.4,571589.5 6327505)" 

"LINESTRING(571927 6327619.2,571906.899999999 6327612.4,571826.700000003 6327586.3,571824.343590402 6327585.48932789,571770.600000001 6327567,571718.700000003 6327549.9,571670.899999999 6327532.4,571589.5 6327505)" 

I want the result of sql say that it match ? 

The difference is only this point : 571824.343590402 6327585.48932789 (add by an app) and this point is very close from the first line : 1.98930589140335e-09 m so, can i add a tolerance to compare ? 

Thanks. 
-- 

	
	

	[ http://www.ledepartement.fr/ | 
                
               ] 	Guillaume ARNAUD 
Technicien SIG 
Cellule SIGD 
Direction des systèmes informatiques et de télécommunication 
Pôle coordination et ressources 
Tél : 05 63 91 82 37 
[ mailto:%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20guillaume.arnaud at ledepartement82.fr | 
                  guillaume.arnaud at ledepartement82.fr
                   ] 
	

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