Transform the values of a pixel image from numeric values into a factor.
# S3 method for im
cut(x, ...)A pixel image (object of class "im") with
pixel values that are a factor.
See im.object.
A pixel image.
An object of class "im".
Arguments passed to cut.default.
They determine the breakpoints for the mapping from numerical values to
factor values. See cut.default.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
and Rolf Turner rolfturner@posteo.net
This simple function applies the generic cut operation
to the pixel values of the image x. The range of pixel values
is divided into several intervals, and each
interval is associated with a level of a factor.
The result is another pixel image,
with the same window and pixel grid as
x, but with the numeric value of each pixel discretised
by replacing it by the factor level.
This function is a convenient way to inspect an image and to obtain summary statistics. See the examples.
To select a subset of an image, use the subset operator
[.im instead.
cut,
im.object
# artificial image data
Z <- setcov(square(1))
Y <- cut(Z, 3)
Y <- cut(Z, breaks=seq(0,1,length=5))
# cut at the quartiles
# (divides the image into 4 equal areas)
Y <- cut(Z, quantile(Z))
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