# Extract.leverage.ppm

From spatstat v1.41-1
by Adrian Baddeley

##### Extract Subset of Leverage Object

Extract a subset of a leverage map, or extract the leverage values at specified locations.

##### Usage

```
## S3 method for class 'leverage.ppm':
[(x, i, ...)
```

##### Arguments

- x
- A leverage object (of class
`"leverage.ppm"`

) computed by`leverage.ppm`

. - i
- Subset index (passed to
`[.im`

). Either a spatial window (object of class`"owin"`

) or a spatial point pattern (object of class`"ppp"`

). - ...
- Further arguments passed to
`[.im`

, especially the argument`drop`

.

##### Details

An object of class `"leverage.ppm"`

contains the values of the
leverage function for a point process model, computed by
`leverage.ppm`

.

This function extracts a designated subset of the leverage values, either as another leverage object, or as a vector of numeric values.

The function `[.leverage.ppm`

is a method for `[`

for the
class `"leverage.ppm"`

. The argument `i`

should be either

- a spatial window (object of class
`"owin"`

) determining a region where the leverage map is required. The result will typically be another leverage map (object of class`leverage.ppm`

). - a spatial point pattern (object of class
`"ppp"`

) specifying locations at which the leverage values are required. The result will be a numeric vector.

`[.im`

, is applied to
the leverage map. If this yields a pixel image, then the result of
`[.leverage.ppm`

is another leverage object. Otherwise,
a vector containing the numeric values of leverage is returned.
##### Value

- Another object of class
`"leverage.ppm"`

, or a vector of numeric values of leverage.

##### See Also

##### Examples

```
fit <- ppm(cells, ~x)
lev <- leverage(fit)
b <- owin(c(0.1, 0.3), c(0.2, 0.4))
lev[b]
lev[cells]
```

*Documentation reproduced from package spatstat, version 1.41-1, License: GPL (>= 2)*

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