R: Create Point Pattern on Linear Network

lpp {spatstat} | R Documentation

## Create Point Pattern on Linear Network

### Description

Creates an object of class `"lpp"` that represents a point pattern on a linear network.

### Usage

    lpp(X, L, ...)

### Arguments

`X` | Locations of the points. A matrix or data frame of coordinates, or a point pattern object (of class `"ppp"`) or other data acceptable to `as.ppp`.
`L` | Linear network (object of class `"linnet"`).
`...` | Ignored.

### Details

This command creates an object of class `"lpp"` that represents a point pattern on a linear network.

Normally `X` is a point pattern. The points of `X` should lie on the lines of `L`.

Alternatively `X` may be a matrix or data frame containing at least two columns.

- Usually the first two columns of `X` will be interpreted as spatial coordinates, and any remaining columns as marks.

- An exception occurs if `X` is a data frame with columns named `x`, `y`, `seg` and `tp`. Then `x` and `y` will be interpreted as spatial coordinates, and `seg` and `tp` as local coordinates, with `seg` indicating which line segment of `L` the point lies on, and `tp` indicating how far along the segment the point lies (normalised to 1). Any remaining columns will be interpreted as marks.

- Another exception occurs if `X` is a data frame with columns named `seg` and `tp`. Then `seg` and `tp` will be interpreted as local coordinates, as above, and the spatial coordinates `x,y` will be computed from them. Any remaining columns will be interpreted as marks.

If `X` is missing or `NULL`, the result is an empty point pattern (i.e. containing no points).

### Value

An object of class `"lpp"`. Also inherits the class `"ppx"`.

### Note on changed format

The internal format of `"lpp"` objects was changed in spatstat version `1.28-0`. Objects in the old format are still handled correctly, but computations are faster in the new format. To convert an object `X` from the old format to the new format, use `X <- lpp(as.ppp(X), as.linnet(X))`.

### Author(s)

Ang Qi Wei aqw07398@hotmail.com and Adrian Baddeley Adrian.Baddeley@curtin.edu.au

### See Also

Installed datasets which are `"lpp"` objects: `chicago`, `dendrite`, `spiders`.

See `as.lpp` for converting data to an `lpp` object.

See `methods.lpp` and `methods.ppx` for other methods applicable to `lpp` objects.

Calculations on an `lpp` object: `intensity.lpp`, `distfun.lpp`, `nndist.lpp`, `nnwhich.lpp`, `nncross.lpp`, `nnfun.lpp`.

Summary functions: `linearK`, `linearKinhom`, `linearpcf`, `linearKdot`, `linearKcross`, `linearmarkconnect`, etc.

Random point patterns on a linear network can be generated by `rpoislpp` or `runiflpp`.

See `linnet` for linear networks.

### Examples

      # letter 'A'
      v <- ppp(x=(-2):2, y=3*c(0,1,2,1,0), c(-3,3), c(-1,7))
      edg <- cbind(1:4, 2:5)
      edg <- rbind(edg, c(2,4))
      letterA <- linnet(v, edges=edg)

      # points on letter A
      xx <- list(x=c(-1.5,0,0.5,1.5), y=c(1.5,3,4.5,1.5))
      X <- lpp(xx, letterA)

      plot(X)
      X
      summary(X)

      # empty pattern
      lpp(L=letterA)

[Package spatstat version 1.54-0 Index]