# formula.fv

##### Extract or Change the Plot Formula for a Function Value Table

Extract or change the default plotting formula
for an object of class `"fv"`

(function value table).

##### Usage

```
# S3 method for fv
formula(x, …)
```formula(x, …) <- value

# S3 method for fv
formula(x, …) <- value

##### Arguments

- x
An object of class

`"fv"`

, containing the values of several estimates of a function.- …
Arguments passed to other methods.

- value
New value of the formula. Either a

`formula`

or a character string.

##### Details

A function value table
(object of class `"fv"`

, see `fv.object`

)
is a convenient way of storing and plotting
several different estimates of the same function.

The default behaviour of `plot(x)`

for a function value table
`x`

is determined by a formula
associated with `x`

called its *plot formula*.
See `plot.fv`

for explanation about these formulae.

The function `formula.fv`

is a method for the generic command
`formula`

. It extracts the plot formula associated with
the object.

The function `formula<-`

is generic. It changes the formula
associated with an object.

The function `formula<-.fv`

is the method for `formula<-`

for the class `"fv"`

. It changes the plot formula associated with
the object.

##### Value

The result of `formula.fv`

is a character string containing the
plot formula. The result of `formula<-.fv`

is a new object of
class `"fv"`

.

##### See Also

##### Examples

```
# NOT RUN {
K <- Kest(cells)
formula(K)
formula(K) <- (iso ~ r)
# }
```

*Documentation reproduced from package spatstat, version 1.55-1, License: GPL (>= 2)*