spatstat.geom (version 3.3-2)

scanpp: Read Point Pattern From Data File

Description

Reads a point pattern dataset from a text file.

Usage

scanpp(filename, window, header=TRUE, dir="", factor.marks=NULL, ...)

Value

A point pattern (an object of class "ppp", see ppp.object).

Arguments

filename

String name of the file containing the coordinates of the points in the point pattern, and their marks if any.

window

Window for the point pattern. An object of class "owin".

header

Logical flag indicating whether the first line of the file contains headings for the columns. Passed to read.table.

dir

String containing the path name of the directory in which filename is to be found. Default is the current directory.

factor.marks

Logical vector (or NULL) indicating whether marks are to be interpreted as factors. Defaults to NULL which means that strings will be interpreted as factors while numeric variables will not. See details.

...

Ignored.

Author

Adrian Baddeley and Rolf Turner .

Details

This simple function reads a point pattern dataset from a file containing the cartesian coordinates of its points, and optionally the mark values for these points.

The file identified by filename in directory dir should be a text file that can be read using read.table. Thus, each line of the file (except possibly the first line) contains data for one point in the point pattern. Data are arranged in columns. There should be either two columns (for an unmarked point pattern) or more columns (for a marked point pattern).

If header=FALSE then the first two columns of data will be interpreted as the \(x\) and \(y\) coordinates of points. Remaining columns, if present, will be interpreted as containing the marks for these points.

If header=TRUE then the first line of the file should contain string names for each of the columns of data. If there are columns named x and y then these will be taken as the cartesian coordinates, and any remaining columns will be taken as the marks. If there are no columns named x and y then the first and second columns will be taken as the cartesian coordinates.

If a logical vector is provided for factor.marks the length should equal the number of mark columns (a shorter factor.marks is recycled to this length). This vector is then used to determine which mark columns should be interpreted as factors. Note: Strings will not be interpreted as factors if the corresponding entry in factor.marks is FALSE.

Note that there is intentionally no default for window. The window of observation should be specified. If you really need to estimate the window, use the Ripley-Rasson estimator ripras.

See Also

ppp.object, ppp, as.ppp, ripras

Examples

  ##  files installed with spatstat, for demonstration
  d <- system.file("rawdata", "finpines", package="spatstat.data")
  if(nzchar(d)) {
    W <- owin(c(-5,5), c(-8,2))
    X <- scanpp("finpines.txt", dir=d, window=W)
    print(X)
  }
  d <- system.file("rawdata", "amacrine", package="spatstat.data")
  if(nzchar(d)) {
    W <- owin(c(0, 1060/662), c(0, 1))
    Y <- scanpp("amacrine.txt", dir=d, window=W, factor.marks=TRUE)
    print(Y)
  }