 # How to calculate distance between two geolocation points?

If we know longitude and latitude of the geolocation points, how we can calculate the distance between them?

For example, image this input document:

``````[
{
"location_1": {
"type": "Point",
"coordinates": [
10,
20
]
},
"location_2": {
"type": "Point",
"coordinates": [
10,
30
]
}
}
]
``````

How can we calculate the distance between `location_1` and `location_2`?

Would the distance calculated with `distance = √ ((x2-x1)² + (y2-y1)²)` work for you?

``````> db.coll.findOne()
{
_id: ObjectId("62c43a4128c8b27fda436536"),
location_1: { type: 'Point', coordinates: [ 10, 20 ] },
location_2: { type: 'Point', coordinates: [ 10, 30 ] }
}
``````

Aggregation:

``````[
{
'distance': {
'\$sqrt': {
{
'\$pow': [
{
'\$subtract': [
{
'\$arrayElemAt': [
'\$location_2.coordinates', 0
]
}, {
'\$arrayElemAt': [
'\$location_1.coordinates', 0
]
}
]
}, 2
]
}, {
'\$pow': [
{
'\$subtract': [
{
'\$arrayElemAt': [
'\$location_2.coordinates', 1
]
}, {
'\$arrayElemAt': [
'\$location_1.coordinates', 1
]
}
]
}, 2
]
}
]
}
}
}
}
]
``````

Result:

``````[
{
_id: ObjectId("62c43a4128c8b27fda436536"),
location_1: { type: 'Point', coordinates: [ 10, 20 ] },
location_2: { type: 'Point', coordinates: [ 10, 30 ] },
distance: 10
}
]
``````

Cheers,
Maxime.

1 Like

Hi @MaBeuLux88,

Thanks for the response! Actually, it should be calculated like in this SO answer here.

I just though that maybe I can use some built-in operator for that. Can you tell me where I can submit a proposal for new operators?

I was actually afraid you would say something like that! Well this calculation can also be done as their is also \$cos, \$sin, etc in the trigonometry operators. But my formula is probably good enough if you have all your points within the same city for example.

If this operator exists, I never heard of it.

Feedback & improvements are in this direction though and I like the idea! I would have also liked to find the “\$distance” one that I had to “implement” in here…

https://feedback.mongodb.com/

Cheers,
Maxime.

Yeah, it would be great to have both of these built-in with some operator. Let me submit both suggestions! Submitted. Here is the suggestion, so everyone that would love to see these operators built-in can go and upvote the suggestion.

2 Likes

Looks like it’s already in the backlog actually:

https://jira.mongodb.org/browse/SERVER-2990

I added my vote on it!

1 Like

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