R: Plot objects produced by deldir

plot.deldir {deldir}

R Documentation

Plot objects produced by deldir

Description

This is a method for plot.

Usage

## S3 method for class 'deldir'
plot(x,add=FALSE,wlines=c("both","triang","tess"),
                      showpoints=TRUE,labelPts=FALSE,cex=1,lex=1,
                      cmpnt_col=NULL,cmpnt_lty=NULL,pch=1,xlim=NULL,
                      ylim=NULL,axes=FALSE,xlab=if(axes) "x" else "",
                      ylab=if(axes) "y" else"",showrect=FALSE,asp=1,...)

Arguments

`x`	An object of class "deldir" as returned by the function deldir.
`add`	logical argument; should the plot be added to an existing plot?
`wlines`	"which lines?". I.e. should the Delaunay triangulation be plotted (wlines="triang"), should the Dirichlet tessellation be plotted (wlines="tess"), or should both be plotted (wlines="both", the default) ?
`showpoints`	Logical scalar; should the points being triangulated/tessellated be plotted?
`labelPts`	Logical argument, defaulting to `FALSE`; if `TRUE` then the points plotted will be labelled with their identifiers (as specified by the optional argument `id` of `deldir()`. If `id` was not specified to `deldir()`, then the identifiers default to the indices of the points, which correspond to the row numbers of the matrix "summary" in the output of `deldir()`).
`cex`	The value of the character expansion argument cex to be used with the plotting symbols for plotting the points.
`lex`	The value of the character expansion argument cex to be used by the text function when labelling the points with their identifiers. Used only if `labelPts` is `TRUE`.
`cmpnt_col`	A vector or list specifying the colours to be used for plotting the (up to five) different components of the graphic, explicitly the triangulation, the tessellation, the data points, the point labels and the enclosing rectangle (`x$rw`) in that order. The components of this vector or list may be named, with the names chosen from `"tri","tess","points","labels","rect".` The default is `c(tri=1,tess=1,points=1,labels=1,rect=1)`. If the vector or list is not named, the component names are assumed to be from the default list of names in the given order. Colours may be specified as positive integers, corresponding to the entries of the current `palette()`, or as names of colours (from the list given by `colors()`), or in terms of their RGB components with strings of the form `"#RRGGBB"`. (See Color Specification in `par()`.) If fewer than five colours are given, the missing components are filled in with `1` or `palette()[1]` as is appropriate. If `cmpnt_col` does not have names then the components are simply recycled. If more than five colours are given, the redundant ones are ignored (i.e. only the first five are used).
`cmpnt_lty`	A vector or list (of length two) of line types for plotting the two components of the graphic that consist of lines, i.e. the triangulation and the tessellation. The types may consist of integers between 1 and 6, or of approriate text strings ("solid", "dashed", "dotted", "dotdash", "longdash" or "twodash"; see the discussion of `lty` in `par()`). The components of `cmpnt_lty` (vector or list) may have names (`"tri","tess"`). The default is c(tri=1,tess=2). If a single value is given, the missing one is filled in as `1` or `"solid"` as is appropriate. If more than two values are given, the redundant ones are ignored, i.e. only the first two are used.
`pch`	The plotting symbol for plotting the points. May be either integer or character.
`xlim`	The limits on the x-axis. Defaults to `rw[1:2]` where `rw` is the rectangular window specification returned by deldir().
`ylim`	The limits on the y-axis. Defaults to `rw[3:4]` where `rw` is the rectangular window specification returned by deldir().
`axes`	Logical scalar. Should axes be drawn on the plot?
`xlab`	Label for the x-axis. Defaults to `x` if `axes` is `TRUE` and to the empty string if `axes` is `FALSE`. Ignored if `add=TRUE`.
`ylab`	Label for the y-axis. Defaults to `y` if `axes` is `TRUE` and to the empty string if `axes` is `FALSE`. Ignored if `add=TRUE`.
`showrect`	Logical scalar; show the enclosing rectangle `rw` (see `deldir()`) be plotted?
`asp`	The aspect ratio of the plot; integer scalar or `NA`. Set this argument equal to `NA` to allow the data to determine the aspect ratio and hence to make the plot occupy the complete plotting region in both `x` and `y` directions. This is inadvisable; see the Warning. The `asp` argument is ignored if `add` is `TRUE`.
`...`	Further plotting parameters (e.g. `lw`, `col`) to be passed to `segments()`. (Conceivably one might also use `...` to supply additional arguments to be passed to `points()` or `text()` but this is unlikely.) Note that if `col` is specified as one of the `...` arguments then this is used as the `col` argument of `segments` (and the values of `cmpnt_col[1:2]` are ignored.

Side Effects

A plot of the edges of the Delaunay triangles and/or of the Dirichlet tiles is produced or added to an existing plot. By default the triangles are plotted with solid lines (lty=1) and the tiles with dotted lines (lty=2). In addition the points being triangulated may be plotted.

Warnings

As of release 1.0-8 the argument number of plot.deldir() and plot.tile.list() was changed to labelPts. As a consequence the argument nex of this function has had its name changed to lex.
In previous versions of the deldir package, the aspect ratio was not set. Instead, the shape of the plotting region was set to be square (pty="s"). This practice was suboptimal. To reproduce previous behaviour set asp=NA (and possibly pty="s") in the call to plot.deldir(). Users, unless they really understand what they are doing and why they are doing it, are now strongly advised not to set the value of asp but rather to leave asp equal to its default value of 1. Any other value may distort the tessellation and destroy the perpendicular appearance of lines which are indeed perpendicular. (And conversely may cause lines which are not perpendicular to appear as if they are.)

Author(s)

Rolf Turner rolfurner@posteo.net

Examples

x <- c(2.3,3.0,7.0,1.0,3.0,8.0) + 0.5
y <- c(2.3,3.0,2.0,5.0,8.0,9.0) + 0.5
x <- c(x,1,10,10,1)
y <- c(y,1,1,10,10)
dxy <- deldir(x,y,rw=c(0,11,0,11))
plot(dxy)

# Plots the tessellation, but does not save the results:
deldir(x,y,rw=c(0,11,0,11),plot=TRUE,
       wl="tess",cmpnt_col=c(1,1,2,3,4),labelPts=TRUE)

# Plots the triangulation, but not the tessellation or the points,
# and saves the returned structure:

dxy <- deldir(x,y,rw=c(0,11,0,11),plot=TRUE,wl="triang",wp="none")

# Plot everything:
plot(dxy,cmpnt_col=c("orange","green","red","blue","black"),cmpnt_lty=1,
     labelPts=TRUE,lex=1.5,pch=c(19,9),showrect=TRUE,axes=TRUE)

# Complicated example from He Huang:
# "Linguistic distances".
vldm <- c(308.298557,592.555483,284.256926,141.421356,449.719913,
          733.976839,591.141269,282.842712,1.414214,732.562625)
ldm <- matrix(nrow=5,ncol=5)
ldm[row(ldm) > col(ldm)]  <- vldm
ldm[row(ldm) <= col(ldm)] <- 0
ldm <- (ldm + t(ldm))/2
rownames(ldm) <- LETTERS[1:5]
colnames(ldm) <- LETTERS[1:5]

# Data to be triangulated.
id <- c("A","B","C","D","E")
x  <- c(0.5,1,1,1.5,2)
y  <- c(5.5,3,7,6.5,5)
dat_Huang <- data.frame(id = id, x = x, y = y)

# Form the triangulation/tessellation.
dH <- deldir(dat_Huang)

# Plot the triangulation with line widths proportional
# to "linguistic distances".
all_col <- rainbow(100)
i       <- pmax(1,round(100*vldm/max(vldm)))
use_col <- all_col[i]
ind     <- as.matrix(dH$delsgs[,c("ind1","ind2")])
lwv <- ldm[ind]
lwv <- 10*lwv/max(lwv)
plot(dH,wlines="triang",col=use_col,showpoints=FALSE,
     lw=lwv,asp=NA)
with(dH,text(x,y,id,cex=1.5))

[Package deldir version 2.0-4 Index]