# gridweights

##### Compute Quadrature Weights Based on Grid Counts

Computes quadrature weights for a given set of points, using the ``counting weights'' for a grid of rectangular tiles.

- Keywords
- spatial

##### Usage

`gridweights(X, nx, ny, window=NULL)`

##### Arguments

- X
- Data defining a point pattern.
- nx
- Number of tiles in each row of the rectangular grid.
- ny
- Number of tiles in each column of the rectangular grid.
- window
- Default window for the point pattern

##### Details

This function computes a set of quadrature weights
for a given pattern of points
(typically comprising both ``data'' and `dummy'' points).
See `quad.object`

for an explanation of quadrature
weights and quadrature schemes.

The weights are computed by the ``counting weights'' rule
based on a regular grid of rectangular tiles.
First `X`

and (optionally) `window`

are converted into a
point pattern object. Then the bounding rectangle of the window of
the point pattern is
divided into a regular $nx \times ny$ grid of rectangular tiles.
The weight attached to a point of `X`

is the area of the tile
in which it lies, divided by the number of points of `X`

lying in
that tile.

##### Value

- Vector of nonnegative weights for each point in
`X`

.

##### See Also

##### Examples

```
library(spatstat)
Q <- quadscheme(runifpoispp(10))
X <- as.ppp(Q) # data and dummy points together
w <- gridweights(X, 10, 10)
```

*Documentation reproduced from package spatstat, version 1.0-1, License: GPL version 2 or newer*