View source: R/spatial_matrices.R

circular_window | R Documentation |

Create a matrix that can be used as a window when working with rasters. It uses a radius to set to 0 the weights of pixels that are farther than this distance. This is helpful to create circular focals.

```
circular_window(radius, res)
```

`radius` |
The size in metres of the radius of the circular focal |

`res` |
The width in metres of a pixel. It is assumed that pixels are squares. |

The original function comes from here: https://scrogster.wordpress.com/2012/10/05/applying-a-circular-moving-window-filter-to-raster-data-in-r/ but we reworked it to make it faster and to ensure that the result is a matrix with odd dimensions.

A binary weight matrix

```
# wide of 100 metres for pixels of 2 metres
window <- circular_window(100, 2)
# row standardisation
window_row_std <- window / sum(window)
```

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