as.lpp {spatstat.linnet}

Convert Data to a Point Pattern on a Linear Network

Description

Convert various kinds of data to a point pattern on a linear network.

Usage

  as.lpp(x=NULL, y=NULL, seg=NULL, tp=NULL, ...,
         marks=NULL, L=NULL, check=FALSE, sparse)

Arguments

x, y

Vectors of cartesian coordinates, or any data acceptable to xy.coords. Alternatively x can be a point pattern on a linear network (object of class "lpp") or a planar point pattern (object of class "ppp").

seg, tp

Optional local coordinates. Vectors of the same length as x,y. See Details.

...

Ignored.

marks

Optional marks for the point pattern. A vector or factor with one entry for each point, or a data frame or hyperframe with one row for each point.

L

Linear network (object of class "linnet") on which the points lie.

check

Logical. Whether to check the validity of the spatial coordinates.

sparse

Optional logical value indicating whether to store the linear network data in a sparse matrix representation or not. See linnet.

Details

This function converts data in various formats into a point pattern on a linear network (object of class "lpp").

The possible formats are:

• x is already a point pattern on a linear network (object of class "lpp"). Then x is returned unchanged.

• x is a planar point pattern (object of class "ppp"). Then x is converted to a point pattern on the linear network L using lpp.

• x,y,seg,tp are vectors of equal length. These specify that the ith point has Cartesian coordinates (x[i],y[i]), and lies on segment number seg[i] of the network L, at a fractional position tp[i] along that segment (with tp=0 representing one endpoint and tp=1 the other endpoint of the segment).

• x,y are missing and seg,tp are vectors of equal length as described above.

• seg,tp are NULL, and x,y are data in a format acceptable to xy.coords specifying the Cartesian coordinates.

• Only the arguments x and L are given, and x is a data frame with one of the following types:

  • two columns labelled seg,tp interpreted as local coordinates on the network.

  • two columns labelled x,y interpreted as Cartesian coordinates.

  • four columns labelled x,y,seg,tp interpreted as Cartesian coordinates and local coordinates.

Value

A point pattern on a linear network (object of class "lpp").

Author(s)

Adrian Baddeley [e-mail]

and Rolf Turner [e-mail]

See Also

lpp.

Examples

   A <- as.psp(simplenet)
   X <- runifpointOnLines(10, A)
   is.ppp(X)
   Y <- as.lpp(X, L=simplenet)