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I'm creating an app using a map and I have to place points on it. The problem is that when the points are nearby, the user can't see the difference. So, I need to regroup the points.

I receive JSONs like that:

[{"id": "1", "x": 253, "y": 144}, 
{"id": "2", "x": 142, "y": 355}, 
{"id": "3", "x": 175, "y": 330}, 
{"id": "4", "x": 140, "y": 5}, 
{"id": "5", "x": 307, "y": 306}, 
{"id": "6", "x": 233, "y": 304}, 
{"id": "7", "x": 212, "y": 163}, 
{"id": "8", "x": 202, "y": 163}, 
{"id": "9", "x": 204, "y": 171}]

And i need to regroup point with 20px difference in biggest point with coord of the average of all other points. It's deal a JSON like that:

[{"id": ["1"], "x": 253, "y": 144}, 
{"id": ["2"], "x": 142, "y": 355}, 
{"id": ["3"], "x": 175, "y": 330}, 
{"id": ["4"], "x": 140, "y": 5}, 
{"id": ["5"], "x": 307, "y": 306}, 
{"id": ["6"], "x": 233, "y": 304}, 
{"id": ["7","8","9"], "x": 206, "y": 165}]

I just need an algorithm to help me to build my own code.

Thank you for all help you can give to me.

takesuma
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  • What do you mean by circle of points? How does your recursive function work? You need to elaborate a little bit more. – Can Bayar Jul 09 '20 at 12:34
  • My tests was just failing so i don't want to trouble you with that. A circle of point is when A is nearby to B B is nearby to C C is nearby to A – takesuma Jul 09 '20 at 12:49
  • How do you define the difference of two points? What is "20px difference"? – dibery Jul 09 '20 at 12:50
  • I have made a condition: item1.id != item2.id && (item1.x >= item2.x-radius && item1.x <= item2.x+radius && item1.y >= item2.y-radius && item1.y <= item2.y+radius) – takesuma Jul 09 '20 at 12:52
  • x and y positions are in number of pixels – takesuma Jul 09 '20 at 12:54
  • If point pair (A, B) and (B, C) are < 20px but pair (A, C) is not, do ABC group together? – dibery Jul 09 '20 at 13:12

1 Answers1

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Euclidian distance is the shortest path between two points and calculated as

sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2))

Just iterate through your list of points from the top to the bottom and if the Euclidean distance between any two points is less than 20, remove the second point or group it with the first one, so you won't have to process it again. You can then calculate the average location of that group if you want to.

Can Bayar
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