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POordering shuffled points that can be joined to form a polygon (in python)
 

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  1. POordering shuffled points that can be joined to form a polygon (in python)
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    <p>I have a collection of points that join to form a polygon in 2D cartesian space. It is in the form of a python list of tuples</p> <pre><code>[(x1, y1), (x2, y2), ... , (xn, yn)] </code></pre> <p>the problem is the join them and form a polygon in a graph. (I'm using matplotlib.path)</p> <p>I made a function to do this. It works as follows:</p> <p>it goes to first point ie (x1, y1) and joins a line to next point ie (x2, y2) and a line from (x2, y2) to (x3, y3) and so on .. till the end which is (xn, yn). It closes the polygon by joining (xn, yn) to (x1, y1). </p> <p>The problem is the list containing these points does not contain the points in the right order so that results in bad drawings like these(Every closed polygon is colored automatically).</p> <p><strong>Example:</strong></p> <p>for this list of vertices = `[(-0.500000050000005, -0.5), (-0.499999950000005, 0.5), (-0.500000100000005, -1.0), (-0.49999990000000505, 1.0), (0.500000050000005, -0.5), (-1.0000000250000025, -0.5), (1.0000000250000025, -0.5), (0.499999950000005, 0.5), (-0.9999999750000024, 0.5), (0.9999999750000024, 0.5), (0.500000100000005, -1.0), (0.49999990000000505, 1.0), (-1.0, 0.0), (-0.0, -1.0), (0.0, 1.0), (1.0, 0.0), (-0.500000050000005, -0.5)]</p> <p><strong>The points:</strong> <img src="https://i.stack.imgur.com/n9MIa.png" alt="enter image description here"></p> <p><strong>Bad order of points results in:</strong> <img src="https://i.stack.imgur.com/9B3W0.png" alt="enter image description here"></p> <p><strong>Correct way to join:</strong> <img src="https://i.stack.imgur.com/YkoLH.png" alt="enter image description here"></p> <p>Is there any good (and easy if possible) algorithm to reorder the points to correct order? `</p>
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    1. COplease add some example data
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      1. USbmu
    2. COThis doesn't sound like the most general solution, but have you tried connecting each point to the closest neighbor?
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      1. USLev Levitsky
    3. COAlso have a look at [this](http://stackoverflow.com/questions/5278801/validity-of-algorithm-for-creation-of-a-non-self-intersecting-polygon) and maybe [this](http://stackoverflow.com/questions/1510310/connect-points-and-compute-area).
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      1. POordering shuffled points that can be joined to form a polygon (in python)
      1. USLev Levitsky
 

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