# Stuck with trying to remove points close to the edge, how can I do this?

**URL:** <https://discourse.processing.org/t/stuck-with-trying-to-remove-points-close-to-the-edge-how-can-i-do-this/30939>\
**Category:** Coding Questions\
**Created:** [June 28, 2021, 10:06am UTC](https://discourse.processing.org/t/stuck-with-trying-to-remove-points-close-to-the-edge-how-can-i-do-this/30939 "2021-06-28T10:06:08Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![alt](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/alt/32/10934_2.png) [@alt](https://discourse.processing.org/u/alt)\
**Post date:** [June 28, 2021, 10:06am UTC](https://discourse.processing.org/t/stuck-with-trying-to-remove-points-close-to-the-edge-how-can-i-do-this/30939/1 "2021-06-28T10:06:08Z")

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I have a problem, I’m trying to remove “stations” or points less than a certain length from the edge, let’s say, 120px from the edge. Now, I tried using a function that removes the stations if they get too close, but that didn’t work. So now, I’m a bit confused as to what to do.

[https://editor.p5js.org/IamRifki/sketches/ozXCkoPhF](https://editor.p5js.org/IamRifki/sketches/ozXCkoPhF)

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**Author:** ![KumuPaul](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/kumupaul/32/13072_2.png) [@KumuPaul](https://discourse.processing.org/u/KumuPaul)\
**Post date:** [June 28, 2021, 8:03pm UTC](https://discourse.processing.org/t/stuck-with-trying-to-remove-points-close-to-the-edge-how-can-i-do-this/30939/2 "2021-06-28T20:03:44Z")

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I’ve had to make a lot of inferences about what exactly you are trying to do, but I’m seeing two issues:

1. When you are randomly generating stations, you are assigning them by index. This makes a sparse array. That is, an array with values for certain indices but not for other indices (for example you might have any array with values at only `array[3]` and `array[7]` and this would have a `length` of 8 but it would not have values at any other positions. I.e. `array[0]` would return undefined). The result of this is that you get errors because you try to reference properties on the `station` variable when it is undefined.

```auto
      // This makes a sparse matrix
      if (bounds)
        gridStations[j * grid + i] = new Station(point);

```

This is were you get an error:

```javascript
      // Because gridStations is sparse, station will sometimes be undefined
      let station = gridStations[int(random(gridStations.length))];

      // code that assumes station is not null or undefined...

```

Because you are only getting stations randomly I think you can simply add new stations to the end of the array using `gridStations.push(...)`.

1. The parameters you are passing to the `pointInRectBounds` function do not make sense:

```auto
      let bounds = pointInRectBounds(
        point[0],
        point[1],
        // left
        width - (width / grid + 1),
        // top
        height - (height / grid + 1),
        // width
        width - (width - (width / grid + 1)),
        // height
        height - (height - (height / grid + 1))
      );

```

if you are trying to avoid placing stations within one grid box of the edge, then the left value you want is just the width of a single grid square: `width / grid`, likewise the top of your bounding box will be the height if a single grid square `height / grid`. The width and height of your bounding box will bet two grid squares less then the total dimension (i.e. `width - 2 * (width / grid)`). Here’s what I think you would want:

```auto
      let bounds =
          pointInRectBounds(
            point[0],
            point[1],
            width / grid,
            height / grid,
            width - (width / grid) * 2,
            height - (height / grid) * 2
          );

```