# split.msr

##### Divide a Measure into Parts

Decomposes a measure into components, each component being a measure.

##### Usage

```
# S3 method for msr
split(x, f, drop = FALSE, …)
```

##### Arguments

- x
Measure (object of class

`"msr"`

) to be decomposed.- f
Factor or tessellation determining the decomposition. Argument passed to

`split.ppp`

. See Details.- drop
Logical value indicating whether empty components should be retained in the list (

`drop=FALSE`

, the default) or deleted (`drop=TRUE`

).- …
Ignored.

##### Details

An object of class `"msr"`

represents a signed (i.e. real-valued)
or vector-valued measure in the spatstat package.
See `msr`

for explanation.

This function is a method for the generic
`split`

. It divides the measure `x`

into
components, each of which is a measure.

A measure `x`

is represented in spatstat by
a finite set of sample points with values attached to them.
The function `split.msr`

divides this pattern of sample points
into several sub-patterns of points using `split.ppp`

.
For each sub-pattern, the values attached to these points are
extracted from `x`

, and these values and sample points
determine a measure, which is a
component or piece of the original `x`

.

The argument `f`

can be missing, if the sample points of `x`

are multitype points. In this case, `x`

represents a measure
associated with marked spatial locations, and the command `split(x)`

separates `x`

into a list of component measures, one for each
possible mark.

Otherwise the argument `f`

is passed to `split.ppp`

.
It should be either a factor (of length equal to the number of
sample points of `x`

) or a tessellation (object of class
`"tess"`

representing a division of space into tiles)
as documented under `split.ppp`

.

##### Value

A list, each of whose entries is a measure (object of class
`"msr"`

).

##### See Also

##### Examples

```
# NOT RUN {
## split by tessellation
a <- residuals(ppm(cells ~ x))
aa <- split(a, dirichlet(runifpoint(4)))
aa
sapply(aa, integral)
## split by type of point
b <- residuals(ppm(amacrine ~ marks + x))
bb <- split(b)
bb
# }
```

*Documentation reproduced from package spatstat, version 1.49-0, License: GPL (>= 2)*