# as.ppp

##### Convert Data To Class ppp

Tries to coerce any reasonable kind of data to a spatial point pattern
(an object of class `"ppp"`

)
for use by the spatstat package).

##### Usage

`as.ppp(X, …, fatal=TRUE)` # S3 method for ppp
as.ppp(X, …, fatal=TRUE)

# S3 method for psp
as.ppp(X, …, fatal=TRUE)

# S3 method for quad
as.ppp(X, …, fatal=TRUE)

# S3 method for matrix
as.ppp(X, W=NULL, …, fatal=TRUE)

# S3 method for data.frame
as.ppp(X, W=NULL, …, fatal=TRUE)

# S3 method for influence.ppm
as.ppp(X, …)

# S3 method for default
as.ppp(X, W=NULL, …, fatal=TRUE)

##### Arguments

- X
Data which will be converted into a point pattern

- W
Data which define a window for the pattern, when

`X`

does not contain a window. (Ignored if`X`

contains window information.)- …
Ignored.

- fatal
Logical value specifying what to do if the data cannot be converted. See Details.

##### Details

Converts the dataset `X`

to a point pattern
(an object of class `"ppp"`

; see `ppp.object`

for
an overview).

This function is normally used to convert an existing point pattern
dataset, stored in another format, to the `"ppp"`

format.
To create a new point pattern from raw data such as \(x,y\)
coordinates, it is normally easier to use the creator function
`ppp`

.

The function `as.ppp`

is generic, with methods for the
classes `"ppp"`

, `"psp"`

, `"quad"`

, `"matrix"`

,
`"data.frame"`

and a default method.

The dataset `X`

may be:

an object of class

`"ppp"`

an object of class

`"psp"`

a point pattern object created by the spatial library

an object of class

`"quad"`

representing a quadrature scheme (see`quad.object`

)a matrix or data frame with at least two columns

a structure with entries

`x`

,`y`

which are numeric vectors of equal lengtha numeric vector of length 2, interpreted as the coordinates of a single point.

In the last three cases, we need the second argument `W`

which is converted to a window object
by the function `as.owin`

.
In the first four cases, `W`

will be ignored.

If `X`

is a line segment pattern (an object of class `psp`

)
the point pattern returned consists of the endpoints of the segments.
If `X`

is marked then the point pattern returned will also be
marked, the mark associated with a point being the mark of the segment
of which that point was an endpoint.

If `X`

is a matrix or data frame, the first and second columns will
be interpreted as the \(x\) and \(y\) coordinates respectively.
Any additional columns will be interpreted as marks.

The argument `fatal`

indicates what to do when
`W`

is missing and `X`

contains no
information about the window. If `fatal=TRUE`

, a fatal error
will be generated; if `fatal=FALSE`

, the
value `NULL`

is returned.

In the spatial library, a point pattern is represented in either of the following formats:

(in spatial versions 1 to 6) a structure with entries

`x`

,`y`

`xl`

,`xu`

,`yl`

,`yu`

(in spatial version 7) a structure with entries

`x`

,`y`

and`area`

, where`area`

is a structure with entries`xl`

,`xu`

,`yl`

,`yu`

where `x`

and `y`

are vectors of equal length
giving the point coordinates, and `xl`

, `xu`

, `yl`

,
`yu`

are numbers giving the dimensions of a rectangular window.

Point pattern datasets can also be created by the function
`ppp`

.

##### Value

An object of class `"ppp"`

(see `ppp.object`

)
describing the point pattern and its window of observation.
The value `NULL`

may also be returned; see Details.

##### See Also

##### Examples

```
# NOT RUN {
xy <- matrix(runif(40), ncol=2)
pp <- as.ppp(xy, c(0,1,0,1))
# Venables-Ripley format
# check for 'spatial' package
spatialpath <- system.file(package="spatial")
if(nchar(spatialpath) > 0) {
require(spatial)
towns <- ppinit("towns.dat")
pp <- as.ppp(towns) # converted to our format
detach(package:spatial)
}
xyzt <- matrix(runif(40), ncol=4)
Z <- as.ppp(xyzt, square(1))
# }
```

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