# cut.ppp

From spatstat v1.18-1
by Adrian Baddeley

##### Classify Points in a Point Pattern

Classifies the points in a point pattern into distinct types according to the numerical marks in the pattern, or according to another variable.

##### Usage

```
## S3 method for class 'ppp':
cut(x, z=marks(x), ...)
```

##### Arguments

- x
- A two-dimensional point pattern.
An object of class
`"ppp"`

. - z
- Data determining the classification. A numeric vector, a factor, a pixel image, or a tessellation. Defaults to the vector of marks of the point pattern.
- ...
- Arguments passed to
`cut.default`

. They determine the breakpoints for the mapping from numerical values in`z`

to factor values in the output. See

##### Details

This function has the effect of classifying each point in the point
pattern `x`

into one of several possible types. The
classification is based on the dataset `z`

, which may be either

- a factor (of length equal to the number of points in
`z`

) determining the classification of each point in`x`

. Levels of the factor determine the classification. - a numeric vector (of length equal to the number of points in
`z`

). The range of values of`z`

will be divided into bands (the number of bands is determined by`...`

) and`z`

will be converted to a factor using`cut.default`

. - a pixel image (object of class
`"im"`

). The value of`z`

at each point of`x`

will be used as the classifying variable. - a tessellation (object of class
`"tess"`

, see`tess`

). Each point of`x`

will be classified according to the tile of the tessellation into which it falls.

`z`

to be the vector of marks in
`x`

. If the marks are numeric, then the range of values
of the numerical marks is divided into several intervals, and each
interval is associated with a level of a factor.
The result is a
marked point pattern, with the same window and point locations as
`x`

, but with the numeric mark of each point discretised
by replacing it by the factor level.
This is a convenient way to transform a marked point pattern
which has numeric marks into a multitype point pattern,
for example to plot it or analyse it. See the examples. To select some points from a point pattern, use the subset operator
`[.ppp`

instead.

##### Value

- A multitype point pattern, that is, a point pattern object
(of class
`"ppp"`

) with a`marks`

vector that is a factor.

##### See Also

##### Examples

```
# (1) cutting based on numeric marks of point pattern
data(longleaf)
# Longleaf Pines data
# the marks are positive real numbers indicating tree diameters.
<testonly># smaller dataset
longleaf <- longleaf[seq(1, longleaf$n, by=80)]</testonly>
plot(longleaf)
# cut the range of tree diameters into three intervals
long3 <- cut(longleaf, breaks=3)
plot(long3)
# adult trees defined to have diameter at least 30 cm
long2 <- cut(longleaf, breaks=c(0,30,100), labels=c("Sapling", "Adult"))
plot(long2)
plot(long2, cols=c("green","blue"))
# (2) cutting based on another numeric vector
# Divide Swedish Pines data into 3 classes
# according to nearest neighbour distance
data(swedishpines)
plot(cut(swedishpines, nndist(swedishpines), breaks=3))
# (3) cutting based on tessellation
# Divide Swedish Pines study region into a 4 x 4 grid of rectangles
# and classify points accordingly
tes <- tess(xgrid=seq(0,96,length=5),ygrid=seq(0,100,length=5))
plot(cut(swedishpines, tes))
plot(tes, lty=2, add=TRUE)
```

*Documentation reproduced from package spatstat, version 1.18-1, License: GPL (>= 2)*

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