# plot.fv

##### Plot Function Values

Plot method for the class `"fv"`

.

##### Usage

```
## S3 method for class 'fv':
plot(x, fmla, \dots, subset=NULL, lty=NULL, col=NULL, lwd=NULL,
xlim=NULL, ylim=NULL, xlab=NULL, ylab=NULL, ylim.covers=NULL,
legend=!add, legendpos="topleft", legendavoid=missing(legendpos),
legendmath=TRUE, legendargs=list(),
shade=NULL, shadecol="grey", add=FALSE, log="", limitsonly=FALSE)
```

##### Arguments

- x
- An object of class
`"fv"`

, containing the variables to be plotted or variables from which the plotting coordinates can be computed. - fmla
- an R language formula determining which variables or expressions are plotted. Either a formula object, or a string that can be parsed as a formula. See Details.
- subset
- (optional) subset of rows of the data frame that will be plotted.
- lty
- (optional) numeric vector of values of the graphical parameter
`lty`

controlling the line style of each plot. - col
- (optional) numeric vector of values of the graphical parameter
`col`

controlling the colour of each plot. - lwd
- (optional) numeric vector of values of the graphical parameter
`lwd`

controlling the line width of each plot. - xlim
- (optional) range of x axis
- ylim
- (optional) range of y axis
- xlab
- (optional) label for x axis
- ylab
- (optional) label for y axis
- ...
- Extra arguments passed to
`plot.default`

. - ylim.covers
- Optional vector of $y$ values that must be included in the
$y$ axis. For example
`ylim.covers=0`

will ensure that the $y$ axis includes the origin. - legend
- Logical flag or
`NULL`

. If`legend=TRUE`

, the algorithm plots a legend in the top left corner of the plot, explaining the meaning of the different line types and colours. - legendpos
- The position of the legend. Either a character string keyword
(see
`legend`

for keyword options) or a pair of coordinates in the format`list(x,y)`

. Alternatively if`legend`

- legendavoid
- Whether to avoid collisions between the legend and the graphics.
Logical value.
If
`TRUE`

, the code will check for collisions between the legend box and the graphics, and will override`legendpos`

if a collision occur - legendmath
- Logical. If
`TRUE`

, the legend will display the mathematical notation for each curve. If`FALSE`

, the legend text is the identifier (column name) for each curve. - legendargs
- Named list containing additional arguments to be passed to
`legend`

controlling the appearance of the legend. - shade
- An index that identifies two columns of
`x`

. When the corresponding curves are plotted, the region between the curves will be shaded in light grey. Often used for displaying simulation envelopes, by setting`shade=c("hi",`

- shadecol
- The colour to be used in the
`shade`

plot. A character string or an integer specifying a colour. - add
- Logical. Whether the plot should be added to an existing plot
- log
- A character string which contains
`"x"`

if the x axis is to be logarithmic,`"y"`

if the y axis is to be logarithmic and`"xy"`

or`"yx"`

if both axes are to be logarithmic. - limitsonly
- Logical. If
`FALSE`

, plotting is performed normally. If`TRUE`

, no plotting is performed at all; just the $x$ and $y$ limits of the plot are computed and returned.

##### Details

This is the `plot`

method for the class `"fv"`

.

The use of the argument `fmla`

is like `plot.formula`

, but offers
some extra functionality.

The left and right hand sides of `fmla`

are evaluated,
and the results are plotted against each other
(the left side on the $y$ axis
against the right side on the $x$ axis).

The left and right hand sides of `fmla`

may be
the names of columns of the data frame `x`

,
or expressions involving these names. If a variable in `fmla`

is not the name of a column of `x`

, the algorithm will search for
an object of this name in the environment where `plot.fv`

was
called, and then in the enclosing environment, and so on.

Multiple curves may be specified by a single formula
of the form
`cbind(y1,y2,...,yn) ~ x`

, where `x,y1,y2,...,yn`

are
expressions involving the variables in the data frame.
Each of the variables `y1,y2,...,yn`

in turn will be plotted
against `x`

.
See the examples.

Convenient abbreviations which can be used in the formula are

- the symbol
`.`

which represents all the variables in the data frame (other than the function argument itself); - the symbol
`.x`

which represents the function argument; - the symbol
`.y`

which represents the recommended value of the function.

The value returned by this plot function indicates the meaning of the line types and colours in the plot. It can be used to make a suitable legend for the plot if you want to do this by hand. See the examples.

The argument `shade`

can be used to display critical bands
or confidence intervals. If it is not `NULL`

, then it should be
a subset index for the columns of `x`

, that identifies exactly
2 columns. When the corresponding curves are plotted, the region
between the curves will be shaded in light grey. See the Examples.

The default values of `lty`

, `col`

and `lwd`

can
be changed using `spatstat.options("plot.fv")`

.

Use `type = "n"`

to create the plot region and draw the axes
without plotting any data.

Use `limitsonly=TRUE`

to suppress all plotting
and just compute the $x$ and $y$ limits. This can be used
to calculate common $x$ and $y$ scales for several plots.

##### Value

- Either
`NULL`

, or a data frame giving the meaning of the different line types and colours.

##### See Also

##### Examples

```
K <- Kest(cells)
# K is an object of class "fv"
plot(K, iso ~ r) # plots iso against r
plot(K, sqrt(iso/pi) ~ r) # plots sqrt(iso/r) against r
plot(K, cbind(iso,theo) ~ r) # plots iso against r AND theo against r
plot(K, . ~ r) # plots all available estimates of K against r
plot(K, sqrt(./pi) ~ r) # plots all estimates of L-function
# L(r) = sqrt(K(r)/pi)
plot(K, cbind(iso,theo) ~ r, col=c(2,3))
# plots iso against r in colour 2
# and theo against r in colour 3
plot(K, iso ~ r, subset=quote(r < 0.2))
# plots iso against r for r < 10
# Can't remember the names of the columns? No problem..
plot(K, sqrt(./pi) ~ .x)
# making a legend by hand
v <- plot(K, . ~ r, legend=FALSE)
legend("topleft", legend=v$meaning, lty=v$lty, col=v$col)
# significance bands
KE <- envelope(cells, Kest, nsim=19)
plot(KE, shade=c("hi", "lo"))
# how to display two functions on a common scale
Kr <- Kest(redwood)
a <- plot(K, limitsonly=TRUE)
b <- plot(Kr, limitsonly=TRUE)
xlim <- range(a$xlim, b$xlim)
ylim <- range(a$ylim, b$ylim)
opa <- par(mfrow=c(1,2))
plot(K, xlim=xlim, ylim=ylim)
plot(Kr, xlim=xlim, ylim=ylim)
par(opa)
```

*Documentation reproduced from package spatstat, version 1.31-3, License: GPL (>= 2)*