Meteor: Locate the closest transportation option between two locations

Question

Meteor: Locate the closest transportation option between two locations

I'm currently in the process of developing a carsharing app, and when it comes to setting up rides, I have this kind of data structure stored in my database:

    {
        "_id": "YyPpkCDhTKStGw6CL",
        "authorId": "W6zvbcqit4Mw6a2iK",
        "stages": [
            {
                "caption": "Paris, France",
                "type": "Point",
                "coordinates": [
                    2.3522219000000177,
                    48.856614
                ]
            },
            {
                "caption": "Lyon, France",
                "type": "Point",
                "coordinates": [
                    4.835659,
                    45.764043
                ]
            },
            {
                "caption": "Toulouse, France",
                "type": "Point",
                "coordinates": [
                    1.4442090000000007,
                    43.604652
                ]
            }
        ],
    }

The stages are arranged in the required sequence (Paris -> Lyon -> Toulouse). I have a basic form with two input fields (start and end). My query is: How can I identify the closest ride?

It appears that I need to do something along these lines:

Identify rides where:

stages.X close to start
stages.Y close to end
X < Y

Do you have any thoughts on how I can execute such a search?

javascript mongodb meteor geojson

Answer 1

Answer №1

I stumbled upon a unique method for getting the job done, so here it is:

// Setting up variables and parameters
var startPoint = [2.3522219000000177, 48.856614];
var endPoint = [4.835659, 45.764043];
var maxDistance = 2000; // measured in meters

// Firstly, locate IDs of rides near my starting point
var rideIds = Rides.find({
    stages: {
        $near: {
            $geometry: {
                type: 'Point',
                coordinates: startPoint,
            },
            $maxDistance: maxDistance,
        }
    }
}, {
    fields: {
        _id: 1
    }
}).map(function(item) { return item._id; });

// Next, find rows close to my destination but within the previously found IDs
var matchedRides = Rides.find({
    _id: { $in: rideIds },
    stages: {
        $near: {
            $geometry: {
                type: 'Point',
                coordinates: endPoint,
            },
            $maxDistance: maxDistance,
        }
    }
});

// Loop through the results to filter out cases where points are in incorrect order
var finalResults = [];
matchedRides.forEach(function(row) {
    var distStart = [];
    var distEnd = [];
    _(row.stages).each(function(stage) {
        distStart.push(calculateDistance(stage.coordinates, startPoint));
        distEnd.push(calculateDistance(stage.coordinates, endPoint));
    });

    var nearestStart = _.indexOf(distStart, _.min(distStart));
    var nearestEnd = _.indexOf(distEnd, _.min(distEnd));

    if (nearestStart < nearestEnd)
        finalResults.push(row);
});

// Displaying the final filtered results
console.log(finalResults);

Here's the function used to calculate distance between two points:

calculateDistance = function(p1, p2) {
    var EARTH_RADIUS = 6378137; // Earth’s mean radius in meters
    var deltaLat = rad(p2[0] - p1[0]);
    var deltaLong = rad(p2[1] - p1[1]);
    var a = Math.sin(deltaLat / 2) * Math.sin(deltaLat / 2) +
        Math.cos(rad(p1[0])) * Math.cos(rad(p2[0])) *
        Math.sin(deltaLong / 2) * Math.sin(deltaLong / 2);
    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    var distance = EARTH_RADIUS * c;
    return Math.round(distance); // returns the distance in meters
}

Answer 2

I stumbled upon a unique method for getting the job done, so here it is:

// Setting up variables and parameters
var startPoint = [2.3522219000000177, 48.856614];
var endPoint = [4.835659, 45.764043];
var maxDistance = 2000; // measured in meters

// Firstly, locate IDs of rides near my starting point
var rideIds = Rides.find({
    stages: {
        $near: {
            $geometry: {
                type: 'Point',
                coordinates: startPoint,
            },
            $maxDistance: maxDistance,
        }
    }
}, {
    fields: {
        _id: 1
    }
}).map(function(item) { return item._id; });

// Next, find rows close to my destination but within the previously found IDs
var matchedRides = Rides.find({
    _id: { $in: rideIds },
    stages: {
        $near: {
            $geometry: {
                type: 'Point',
                coordinates: endPoint,
            },
            $maxDistance: maxDistance,
        }
    }
});

// Loop through the results to filter out cases where points are in incorrect order
var finalResults = [];
matchedRides.forEach(function(row) {
    var distStart = [];
    var distEnd = [];
    _(row.stages).each(function(stage) {
        distStart.push(calculateDistance(stage.coordinates, startPoint));
        distEnd.push(calculateDistance(stage.coordinates, endPoint));
    });

    var nearestStart = _.indexOf(distStart, _.min(distStart));
    var nearestEnd = _.indexOf(distEnd, _.min(distEnd));

    if (nearestStart < nearestEnd)
        finalResults.push(row);
});

// Displaying the final filtered results
console.log(finalResults);

Here's the function used to calculate distance between two points:

calculateDistance = function(p1, p2) {
    var EARTH_RADIUS = 6378137; // Earth’s mean radius in meters
    var deltaLat = rad(p2[0] - p1[0]);
    var deltaLong = rad(p2[1] - p1[1]);
    var a = Math.sin(deltaLat / 2) * Math.sin(deltaLat / 2) +
        Math.cos(rad(p1[0])) * Math.cos(rad(p2[0])) *
        Math.sin(deltaLong / 2) * Math.sin(deltaLong / 2);
    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    var distance = EARTH_RADIUS * c;
    return Math.round(distance); // returns the distance in meters
}

Meteor: Locate the closest transportation option between two locations

Answer №1

Similar questions

What is the process for printing a page in plain text format on a matrix-dot printer?

Summing arrays of numbers within an HTML form input and showcasing the final result

Having difficulty with Angular's ng-options feature in a Select element

Using Perl arrays within a PostgreSQL INSERT query

Customize your Vite logger settings using the config plugin

What would be the best way to create a JavaScript function that emulates the functionality of an Upgrade Button?

How can I utilize a custom shader in Three.js to fill a png texture and establish transparency?

The input value remains a string even after it has been converted to a float

Initially, my PDF file does not get selected, except in the Internet Explorer browser

initiating a submission upon the occurrence of an onchange event on an input field of type "file"

Mastering the Sequence of JS Functions (or How Promises Still Confuse Me)

NodeJS refuses to import a file that is not compatible with its structure

What is the best way to include a second (concealed) value in a cell using datatables

Prioritize establishing the connection before guiding the user to a new destination

What is the best way to sum up multiple checkbox values in JavaScript?

JS problem with using for and foreach loops in Node.js

What strategies can be employed to manage three conflicting versions of a single library within a Vite project?

extract the text content from an object

Using Cocoon Gem in Rails 5 to create nested forms within nested forms

Execute the gulp module on the source files