plot.ppp
plot a Spatial Point Pattern
Plot a two-dimensional spatial point pattern
Usage
## S3 method for class 'ppp':
plot(x, main, \dots, chars=NULL, cols=NULL,
use.marks=TRUE, which.marks=1, add=FALSE,
maxsize=NULL, markscale=NULL,zap=0.01)
Arguments
- x
- The spatial point pattern to be plotted.
An object of class
"ppp"
, or data which can be converted into this format byas.ppp()
. - main
- text to be displayed as a title above the plot.
- ...
- extra arguments that will be passed to the plotting functions
plot.default
,points
and/orsymbols
- chars
- plotting character(s) used to plot points.
- cols
- the colour(s) used to plot points.
- use.marks
- logical flag; if
TRUE
, plot points using a different plotting symbol for each mark; ifFALSE
, only the locations of the points will be plotted, usingpoints()
. - which.marks
- Index determining which column of marks to use,
if the marks of
x
are a data frame. A character string or an integer. Defaults to1
indicating the first column of marks. - add
- logical flag; if
TRUE
, just the points are plotted, over the existing plot. A new plot is not created, and the window is not plotted. - maxsize
- maximum size of the circles/squares plotted
when
x
is a marked point pattern with numerical marks. Incompatible withmarkscale
. - markscale
- physical scale factor determining the sizes of the
circles/squares plotted when
x
is a marked point pattern with numerical marks. Incompatible withmaxsize
. - zap
- Fraction between 0 and 1.
When
x
is a marked point pattern with numerical marks,zap
is the smallest mark value (expressed as a fraction of the maximum possible mark) that will be plotted. Any points which ha
Details
This is the plot
method for
point pattern datasets (of class "ppp"
, see ppp.object
).
First the observation window x$window
is plotted.
Then the points themselves are plotted,
in a fashion that depends on their marks,
as follows.
[object Object],[object Object],[object Object],[object Object]
Plotting of the window x$window
is performed by
plot.owin
. This plot may be modified
through the ...
arguments. In particular the
extra argument border
determines
the colour of the window.
Plotting of the points themselves is performed
by the function points
, except for the case of
continuous marks, where it is performed by symbols
.
Their plotting behaviour may be modified through the ...
arguments.
The argument chars
determines the plotting character
or characters used to display the points (in all cases except
for the case of continuous marks). For an unmarked point pattern,
this should be a single integer or character determining a
plotting character (see par("pch")
).
For a multitype point pattern, chars
should be a vector
of integers or characters, of the same length
as levels(x$marks)
, and then the $i$th level or type
will be plotted using character chars[i]
.
If chars
is absent, but there is an extra argument
pch
, then this will determine the plotting character for
all points.
The argument cols
determines the colour or colours used to
display the points. For an unmarked point pattern, or a
marked point pattern with continuous marks, this should be a character string
determining a colour. For a multitype point pattern, cols
should be a character vector, of the same length
as levels(x$marks)
. The $i$th level or type will
be plotted using colour cols[i]
.
If cols
is absent, the colour used to plot all the
points may be determined by the extra argument fg
(for multitype point patterns) or the extra argument col
(for all other cases). Note that col
will also reset the
colour of the window.
The arguments maxsize
and markscale
incompatible. They control the physical size of the circles and
squares which represent the marks in a point pattern with continuous
marks. If markscale
is given, then a mark value of m
is plotted as a circle of radius m * markscale
(if m
is positive) or a square of side abs(m) * markscale
(if m
is negative). If maxsize
is given, then the
largest mark in absolute value, mmax=max(abs(x$marks))
,
will be scaled to have physical size maxsize
.
The user can set the default values of these plotting parameters
using spatstat.options("par.points")
.
To zoom in (to view only a subset of the point pattern at higher
magnification), use the graphical arguments
xlim
and ylim
to specify the rectangular field of view.
The value returned by this plot function can be used to make a suitable legend, as shown in the examples.
Value
NULL
, or a vector giving the correspondence between mark values and plotting characters.
Removing White Space Around The Plot
A frequently-asked question is: How do I remove the white space around
the plot? Currently plot.ppp
uses the base graphics system of
R, so the space around the plot is controlled by parameters
to par
. To reduce the white space, change the
parameter mar
. Typically, par(mar=rep(0.5, 4))
is
adequate, if there are no annotations or titles outside the window.
See Also
Examples
data(cells)
plot(cells)
plot(cells, pch=16)
# make the plotting symbols larger (for publication at reduced scale)
plot(cells, cex=2)
# set it in spatstat.options
oldopt <- spatstat.options(par.points=list(cex=2))
plot(cells)
spatstat.options(oldopt)
# multitype
data(lansing)
plot(lansing)
# marked by a real number
data(longleaf)
plot(longleaf)
# just plot the points
plot(longleaf, use.marks=FALSE)
plot(unmark(longleaf)) # equivalent
# controlling COLOURS of points
plot(cells, cols="blue")
plot(lansing, cols=c("black", "yellow", "green",
"blue","red","pink"))
plot(longleaf, fg="blue")
# make window purple
plot(lansing, border="purple")
# make everything purple
plot(lansing, border="purple", cols="purple", col.main="purple")
# controlling PLOT CHARACTERS
plot(lansing, chars = 11:16)
plot(lansing, chars = c("o","h","m",".","o","o"))
# controlling MARK SCALE
plot(longleaf, markscale=0.1)
# draw circles of DIAMETER equal to nearest neighbour distance
plot(cells %mark% nndist(cells), markscale=1/2)
# making the legend
data(amacrine)
v <- plot(amacrine)
legend(0.2, 1.2, pch=v, legend=names(v))
# point pattern with multiple marks
data(finpines)
plot(finpines, which.marks="height")