CODEWITHSUNDEEP
javascriptcoordinates
Flame_Phoenix
Flame_Phoenix

Reputation: 17574

Check if coordinate belongs to square, given NE and SW corrds of region

Background

I a coordinate and I need to know if it is inside a square. To achieve this I am given the NorthEast and SouthWest coordinates of this square.

Code

So far I came up with the following code:

const isInsideSquare = (center, northEast, southWest) =>
    southWest.lat < center.lat  &&
    northEast.lat  > center.lat &&
    northEast.lng  < center.lng &&
    southWest.lng > center.lng;

However, this code fails with the following example:

const northEast = {lat: 42.1539732831, lng: -4.7027107182};
const southWest = {lat: 36.8340642391, lng: -11.5965440996};
const coord = {lat: 38.7223, lng: -9.1393};

console.log(isInsideSquare(coord, northEat, southWest));   //false

Problem

The problem is that my function returns false, instead of true. As you can see, the coordis inside the square:

https://www.darrinward.com/lat-long/?id=59e70fdf5c8578.99150744

But somehow I am missing it.

Question

What is wrong in my code?

Upvotes: 1

Views: 912

Answers (2)

Thomas
Thomas

Reputation: 12637

on the longitude you deal with a circle, and your angles wrap around, you have to deal with that, or normalizing it somehow

const normalizeDegrees = v => v < 0 ? 360 + v % 360 : v % 360;

const isInsideSquare = (center, northEast, southWest) => (
  southWest.lat < center.lat &&
  northEast.lat > center.lat &&
  normalizeDegrees(center.lng - southWest.lng) < normalizeDegrees(northEast.lng - southWest.lng));

const northEast = {
  lat: 42.1539732831,
  lng: -4.7027107182
};
const southWest = {
  lat: 36.8340642391,
  lng: -11.5965440996
};
const coord = {
  lat: 38.7223,
  lng: -9.1393
};

console.log(isInsideSquare(coord, northEast, southWest));
.as-console-wrapper{top:0;max-height:100%!important}

center is less degrees to the east of southwest than northEast is.

Upvotes: 0

zinovyev
zinovyev

Reputation: 2163

Should be

const isInsideSquare = (center, northEast, southWest) =>
  southWest.lat < center.lat  &&
  northEast.lat  > center.lat &&
  northEast.lng  > center.lng && // <-- this condition reversed
  southWest.lng < center.lng;    // <-- this condition reversed

Cause both latitude and longtitude in the southWest edge are greater than coordinates in the center. And both coordinates in northEast should be lower.

Upvotes: 2

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