Convert Point Pattern to Pixel Image
Converts a point pattern to a pixel image. The value in each pixel is the number of points falling in that pixel, and is typically either 0 or 1.
## S3 method for class 'ppp': pixellate(x, W=NULL, \dots, weights = NULL, padzero=FALSE)
## S3 method for class 'ppp': as.im(X, \dots)
- Point pattern (object of class
- Arguments passed to
as.maskto determine the pixel resolution
- Optional window mask (object of class
"owin") determining the pixel raster.
- Optional vector of weights associated with the points.
- Logical flag indicating whether to set pixel values to zero outside the window.
convert a spatial point pattern
x into a pixel
image, by counting the number of points (or the total weight of
points) falling in each pixel.
as.im.ppp is equivalent to
pixellate.ppp with its default arguments.
pixellate.ppp is more general than
(it has additional arguments for greater flexibility).
The pixel raster (in which points are counted) is determined
by the argument
W if it is present (for
In this case
W should be a binary mask (a window object of
"owin" with type
Otherwise the pixel raster is determined by
extracting the window containing
x and converting it to a
binary pixel mask using
as.mask. The arguments
... are passed to
control the pixel resolution.
NULL, then for each pixel
in the mask, the algorithm counts how many points in
in the pixel. This count is usually either 0 (for a pixel with no data
points in it) or 1 (for a pixel containing one data point) but may be
greater than 1. The result is an image with these counts as its pixel values.
weights is given, it should be a numeric vector of the same
length as the number of points in
x. For each pixel, the
algorithm finds the total weight associated with points in
x that fall
in the given pixel. The result is an image with these total weights
as its pixel values.
By default (if
zeropad=FALSE) the resulting pixel image has the same
spatial domain as the window of the point pattern
zeropad=TRUE then the resulting pixel image has a rectangular
domain; pixels outside the original window are assigned the value zero.
- A pixel image (object of class