Cannot read property 'x' of undefined error

[almirfilho]

Before anything, I'd like to thank you very much for this package!

I don't have an idea why this is happening, but sometimes (apparently randomly) this error occur when calling .getClusterExpansionZoom() method.

Cannot read property 'x' of undefined

Object.getChildren
index.js:84

The getChildren() method tries to read from origin.x, but origin variable is undefined.
The origin var, as we can see, is created in the following line:

var origin = this.trees[clusterZoom + 1].points[clusterId];

It is undefined because (as in one of my debuggings) clusterZoom = 12 and clusterId = 21, and this.trees[13].points only have 19 entries (0 to 18), thus, this.tree[13].points[21] returns undefined.

Any ideas why is that error occurring? Thanks! =)

[mourner]

Hmm, hard to say. Can you reproduce this easily? E.g. within a few clicks? If so, can you set up a simple minimal test case? This shouldn't happen randomly because Supercluster is deterministic.

[almirfilho]

Here @mourner, try to run this. The issue is with the zoom level, I guess.

var supercluster = require('supercluster');
var superCluster = supercluster({radius: 50});
var points = [
  {"properties":null,"geometry":{"coordinates":[-157.738807,21.403821]}},
  {"properties":null,"geometry":{"coordinates":[-157.7339888,21.3993326]}},
  {"properties":null,"geometry":{"coordinates":[-157.734548,21.40033]}},
  {"properties":null,"geometry":{"coordinates":[-157.708681,21.379721]}},
  {"properties":null,"geometry":{"coordinates":[-157.711043,21.385541]}},
  {"properties":null,"geometry":{"coordinates":[-157.7172689,21.393636]}},
  {"properties":null,"geometry":{"coordinates":[-157.7443502,21.4165303]}},
  {"properties":null,"geometry":{"coordinates":[-157.74334,21.413519]}},
  {"properties":null,"geometry":{"coordinates":[-157.709435,21.383292]}},
  {"properties":null,"geometry":{"coordinates":[-157.712649,21.388786]}},
  {"properties":null,"geometry":{"coordinates":[-157.729243,21.398487]}},
  {"properties":null,"geometry":{"coordinates":[-157.729243,21.398487]}},
  {"properties":null,"geometry":{"coordinates":[-157.709189,21.379953]}},
  {"properties":null,"geometry":{"coordinates":[-157.71043,21.384883]}},
  {"properties":null,"geometry":{"coordinates":[-157.709665,21.383786]}},
  {"properties":null,"geometry":{"coordinates":[-157.720091,21.395693]}},
  {"properties":null,"geometry":{"coordinates":[-157.716762,21.3888]}},
  {"properties":null,"geometry":{"coordinates":[-157.711711,21.387149]}},
  {"properties":null,"geometry":{"coordinates":[-157.741526,21.408911]}},
  {"properties":null,"geometry":{"coordinates":[-157.7153218,21.3912362]}},
  {"properties":null,"geometry":{"coordinates":[-157.71704,21.3895139]}},
  {"properties":null,"geometry":{"coordinates":[-157.711032,21.386012]}},
  {"properties":null,"geometry":{"coordinates":[-157.7165599,21.388456]}},
  {"properties":null,"geometry":{"coordinates":[-157.735521,21.399968]}},
  {"properties":null,"geometry":{"coordinates":[-157.7096139,21.381616]}},
  {"properties":null,"geometry":{"coordinates":[-157.764096,21.422697]}},
  {"properties":null,"geometry":{"coordinates":[-157.7447369,21.41656]}},
  {"properties":null,"geometry":{"coordinates":[-157.716935,21.392532]}},
  {"properties":null,"geometry":{"coordinates":[-157.712677,21.38497]}},
  {"properties":null,"geometry":{"coordinates":[-157.713332,21.380847]}},
  {"properties":null,"geometry":{"coordinates":[-157.716933,21.38936]}},
  {"properties":null,"geometry":{"coordinates":[-157.71542,21.3905439]}},
  {"properties":null,"geometry":{"coordinates":[-157.743339,21.41022]}},
  {"properties":null,"geometry":{"coordinates":[-157.7460247,21.4165045]}},
  {"properties":null,"geometry":{"coordinates":[-157.7387108,21.4014343]}},
  {"properties":null,"geometry":{"coordinates":[-157.712387,21.38135]}},
  {"properties":null,"geometry":{"coordinates":[-157.762416,21.4276899]}},
  {"properties":null,"geometry":{"coordinates":[-157.747666,21.414808]}},
  {"properties":null,"geometry":{"coordinates":[-157.739207,21.4247]}},
  {"properties":null,"geometry":{"coordinates":[-157.774142,21.406839]}},
  {"properties":null,"geometry":{"coordinates":[-157.7178999,21.390093]}},
  {"properties":null,"geometry":{"coordinates":[-157.747462,21.389257]}},
  {"properties":null,"geometry":{"coordinates":[-157.744486,21.4108139]}},
  {"properties":null,"geometry":{"coordinates":[-157.71512,21.38752]}},
  {"properties":null,"geometry":{"coordinates":[-157.743692,21.425881]}},
  {"properties":null,"geometry":{"coordinates":[-157.770683,21.412724]}},
  {"properties":null,"geometry":{"coordinates":[-157.7426186,21.4086938]}},
  {"properties":null,"geometry":{"coordinates":[-157.738378,21.426421]}},
  {"properties":null,"geometry":{"coordinates":[-157.722777,21.392695]}},
  {"properties":null,"geometry":{"coordinates":[-157.766212,21.411992]}}
];
superCluster.load(points);

var bbox = [
  -157.78133979848454,
  21.3464786240286,
  -157.66633979563304,
  21.460381588705975
];
var zoom = 12;
var clusters = superCluster.getClusters(bbox, zoom);
var clusterId = clusters[6].properties.cluster_id;

// OK with zoom = 12
console.log(superCluster.getClusterExpansionZoom(clusterId, zoom));
// ERROR with zoom = 11
console.log(superCluster.getClusterExpansionZoom(clusterId, 11));

[mourner]

Oh, yeah, the zoom provided must match the zoom you're getting the cluster from. Would providing a more meaningful error resolve the issue?

[almirfilho]

Or, don't you think that it should return the expansion zoom anyway? (13 for that case) @mourner

[mourner]

No, because clusterId is only valid for a specific zoom value — combined they form a unique identification of a cluster. But I'm thinking about combining them somehow into one number variable to avoid confusion like this and make the API easier.

[almirfilho]

@mourner Agreed. I think tou could use uuids for that. Anyway, I think it would be nice to have this information you just gave me in the Readme, and a better error to avoid confusion of course. Let me know if you need help with that. And thanks again for this package!

[mourner]

@almirfilho opened an issue for this: #43. I think we should definitely do this because it will make the API simpler (no need to pass zoom).

[myflowpl]

I run into the same problem.
But in my case i accidentally set the zoom as string, then '14'+1 = '141' instead of 15.
May be we can do something like this:

var origin = this.trees[parseInt(clusterZoom) + 1].points[clusterId];

and help others avoid this kind of silly mistakes :)

[chriscalip]

For anyone stuck using
"@mapbox/mapbox-gl-supported": "^1.3.0", and have to do "supercluster": "2.3.0"
How to fix?