Turf.js inside() method won't return true

Question

I'm trying to write a script that, using the inside method of Turf.js, that takes user-submitted coordinates and matches it to the corresponding Census tract. The code below, as a test, I believe should return true. It does not.

Those coordinates definitely are Wrigley Field. The tract polygon does envelope it. I linted the two bits of geoJson and they're clean (except for the right-hand rule).

const wrigleyField = [41.947783, -87.655889];
const wrigleyCensusTract = { "type": "Feature", "properties": { "STATEFP10": "17", "COUNTYFP10": "031", "TRACTCE10": "061100", "GEOID10": "17031061100", "NAME10": "611", "NAMELSAD10": "Census Tract 611", "MTFCC10": "G5020", "FUNCSTAT10": "S", "ALAND10": 173037, "AWATER10": 0, "INTPTLAT10": "+41.9491397", "INTPTLON10": "-087.6568035" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ -87.656985, 41.951084 ], [ -87.656858, 41.951086 ], [ -87.656806, 41.951087 ], [ -87.656704, 41.951088 ], [ -87.656661, 41.951088 ], [ -87.656535, 41.951091 ], [ -87.656494, 41.951092 ], [ -87.656325, 41.951094 ], [ -87.656245, 41.951096 ], [ -87.655821, 41.951102 ], [ -87.655653, 41.951105 ], [ -87.655411, 41.951109 ], [ -87.655059, 41.951115 ], [ -87.654685, 41.95112 ], [ -87.654444, 41.951124 ], [ -87.654431, 41.950707 ], [ -87.654395, 41.949459 ], [ -87.654384, 41.949043 ], [ -87.654373, 41.948683 ], [ -87.654344, 41.947698 ], [ -87.654341, 41.947604 ], [ -87.65433, 41.947245 ], [ -87.654576, 41.94724 ], [ -87.654938, 41.947234 ], [ -87.655317, 41.947228 ], [ -87.655565, 41.947225 ], [ -87.655755, 41.947221 ], [ -87.656313, 41.947213 ], [ -87.656325, 41.947212 ], [ -87.656516, 41.947202 ], [ -87.656663, 41.947194 ], [ -87.656849, 41.947184 ], [ -87.657104, 41.94718 ], [ -87.657252, 41.947178 ], [ -87.657382, 41.947176 ], [ -87.657635, 41.947171 ], [ -87.657739, 41.94717 ], [ -87.658784, 41.947154 ], [ -87.659168, 41.947149 ], [ -87.659165, 41.947254 ], [ -87.659167, 41.94733 ], [ -87.659176, 41.947623 ], [ -87.659181, 41.947876 ], [ -87.659186, 41.948059 ], [ -87.65919, 41.94824 ], [ -87.659196, 41.948487 ], [ -87.659204, 41.948785 ], [ -87.65921, 41.948967 ], [ -87.659219, 41.949292 ], [ -87.659229, 41.949598 ], [ -87.659245, 41.950269 ], [ -87.659254, 41.950595 ], [ -87.659257, 41.950685 ], [ -87.659266, 41.950957 ], [ -87.659269, 41.951048 ], [ -87.658928, 41.951052 ], [ -87.657908, 41.951068 ], [ -87.657569, 41.951074 ], [ -87.657468, 41.951075 ], [ -87.657167, 41.951081 ], [ -87.657067, 41.951083 ], [ -87.657014, 41.951083 ], [ -87.656985, 41.951084 ] ] ] } }

const wrigleyPoint = { "type": "Feature", "properties": { "marker-color": "#0f0" }, "geometry": { "type": "Point", "coordinates": wrigleyField } };

console.log(turf.inside(wrigleyPoint, wrigleyCensusTract)); // false

What am I missing? Why does the above snippet not return true?

Thanks!

You sure you got those coords in the right order? on the WF point, specifically. — pvg
Both Google and Leaflet map that point right where it should be. FWIW, Leaflet also maps the tract data properly, too, when compared to official maps. — ryanbmarx
The coords in your polygon, the coords in the docs in the turf.js example are in a different order. Have you tried swapping the wrigleyField coords and seeing what happens? i.e. change to wrigleyField = [ -87.655889, 41.947783]; — pvg

Dylan Hamilton Dylan Hamilton · Accepted Answer · 2017-03-08T13:33:39

The issue is that your point coordinates are swapped. If you switch their places, then it will return true. I just tested this myself with your data and I did get true after swapping the point coordinates. Here is a snippet so you can test it yourself.

p1 = { "type": "Feature", "properties": { "STATEFP10": "17", "COUNTYFP10": "031", "TRACTCE10": "061100", "GEOID10": "17031061100", "NAME10": "611", "NAMELSAD10": "Census Tract 611", "MTFCC10": "G5020", "FUNCSTAT10": "S", "ALAND10": 173037, "AWATER10": 0, "INTPTLAT10": "+41.9491397", "INTPTLON10": "-087.6568035" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ -87.656985, 41.951084 ], [ -87.656858, 41.951086 ], [ -87.656806, 41.951087 ], [ -87.656704, 41.951088 ], [ -87.656661, 41.951088 ], [ -87.656535, 41.951091 ], [ -87.656494, 41.951092 ], [ -87.656325, 41.951094 ], [ -87.656245, 41.951096 ], [ -87.655821, 41.951102 ], [ -87.655653, 41.951105 ], [ -87.655411, 41.951109 ], [ -87.655059, 41.951115 ], [ -87.654685, 41.95112 ], [ -87.654444, 41.951124 ], [ -87.654431, 41.950707 ], [ -87.654395, 41.949459 ], [ -87.654384, 41.949043 ], [ -87.654373, 41.948683 ], [ -87.654344, 41.947698 ], [ -87.654341, 41.947604 ], [ -87.65433, 41.947245 ], [ -87.654576, 41.94724 ], [ -87.654938, 41.947234 ], [ -87.655317, 41.947228 ], [ -87.655565, 41.947225 ], [ -87.655755, 41.947221 ], [ -87.656313, 41.947213 ], [ -87.656325, 41.947212 ], [ -87.656516, 41.947202 ], [ -87.656663, 41.947194 ], [ -87.656849, 41.947184 ], [ -87.657104, 41.94718 ], [ -87.657252, 41.947178 ], [ -87.657382, 41.947176 ], [ -87.657635, 41.947171 ], [ -87.657739, 41.94717 ], [ -87.658784, 41.947154 ], [ -87.659168, 41.947149 ], [ -87.659165, 41.947254 ], [ -87.659167, 41.94733 ], [ -87.659176, 41.947623 ], [ -87.659181, 41.947876 ], [ -87.659186, 41.948059 ], [ -87.65919, 41.94824 ], [ -87.659196, 41.948487 ], [ -87.659204, 41.948785 ], [ -87.65921, 41.948967 ], [ -87.659219, 41.949292 ], [ -87.659229, 41.949598 ], [ -87.659245, 41.950269 ], [ -87.659254, 41.950595 ], [ -87.659257, 41.950685 ], [ -87.659266, 41.950957 ], [ -87.659269, 41.951048 ], [ -87.658928, 41.951052 ], [ -87.657908, 41.951068 ], [ -87.657569, 41.951074 ], [ -87.657468, 41.951075 ], [ -87.657167, 41.951081 ], [ -87.657067, 41.951083 ], [ -87.657014, 41.951083 ], [ -87.656985, 41.951084 ] ] ] } };

p2 = {"type": "Feature", "properties": {}, "geometry": {"type": "Point", "coordinates": [-87.655889, 41.947783]}};

alert(turf.inside(p2, p1))

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Turf.js inside() method won't return true

1 Answers