# Extract.lpp

##### Extract Subset of Point Pattern on Linear Network

Extract a subset of a point pattern on a linear network.

##### Usage

```
## S3 method for class 'lpp':
[(x, i, j, ...)
```

##### Arguments

- x
- A point pattern on a linear network (object of class
`"lpp"`

). - i
- Subset index. A valid subset index in the usual Rsense, indicating which points should be retained
- j
- Spatial window
(object of class
`"owin"`

) delineating the region that should be retained. - ...
- Ignored.

##### Details

This function extracts a designated subset of a point pattern on a linear network.

The function `[.lpp`

is a method for `[`

for the
class `"lpp"`

. It extracts a designated subset of a point pattern.
The argument `i`

should be a subset index in the usual Rsense:
either a numeric vector
of positive indices (identifying the points to be retained),
a numeric vector of negative indices (identifying the points
to be deleted) or a logical vector of length equal to the number of
points in the point pattern `x`

. In the latter case,
the points `(x$x[i], x$y[i])`

for which
`subset[i]=TRUE`

will be retained, and the others
will be deleted.

The argument `j`

, if present, should be a spatial window.
The pattern inside the region will be retained.
*Line segments that cross the boundary of the window
are deleted* in the current implementation.

Use the function `unmark`

to remove marks from a
marked point pattern.

##### Value

- A point pattern on a linear network (of class
`"lpp"`

).

##### See Also

##### Examples

```
# Chicago crimes data - remove cases of assault
chicago[marks(chicago) != "assault"]
```

*Documentation reproduced from package spatstat, version 1.37-0, License: GPL (>= 2)*