Description Usage Arguments Details Value Author(s) See Also Examples

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

1 2 |

`x` |
A point pattern on a linear network (object of class |

`i` |
Subset index. A valid subset index in the usual |

`j` |
Spatial window
(object of class |

`drop` |
Logical value indicating whether to remove unused levels of the marks, if the marks are a factor. |

`snip` |
Logical. If |

`...` |
Ignored. |

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 **R** sense:
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.

The argument `drop`

determines whether to remove
unused levels of a factor, if the point pattern is multitype
(i.e. the marks are a factor) or if the marks are a data frame or hyperframe
in which some of the columns are factors.

The argument `snip`

specifies what to do with segments of
the network which cross the boundary of the window `j`

.
If `snip=FALSE`

, such segments are simply deleted.
If `snip=TRUE`

(the default), such segments are cut into pieces by the
boundary of `j`

, and those pieces which lie inside the window
`ji`

are included in the resulting network.

Use `unmark`

to remove all the marks in a marked point
pattern, and `subset.lpp`

to remove only some columns of marks.

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

).

and \rolf

1 2 3 4 5 6 7 8 9 10 11 12 13 14 | ```
# Chicago crimes data - remove cases of assault
chicago[marks(chicago) != "assault"]
# equivalent to subset(chicago, select=-assault)
# spatial window subset
B <- owin(c(350, 700), c(600, 1000))
plot(chicago)
plot(B, add=TRUE, lty=2, border="red", lwd=3)
op <- par(mfrow=c(1,2), mar=0.6+c(0,0,1,0))
plot(B, main="chicago[B, snip=FALSE]", lty=3, border="red")
plot(chicago[, B, snip=FALSE], add=TRUE)
plot(B, main="chicago[B, snip=TRUE]", lty=3, border="red")
plot(chicago[, B, snip=TRUE], add=TRUE)
par(op)
``` |

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