model.extract {stats} | R Documentation |

## Extract Components from a Model Frame

### Description

Returns the response, offset, subset, weights or other
special components of a model frame passed as optional arguments to
`model.frame`

.

### Usage

model.extract(frame, component)
model.offset(x)
model.response(data, type = "any")
model.weights(x)

### Arguments

`frame, x, data` |
A model frame. |

`component` |
literal character string or name. The name of a
component to extract, such as `"weights"` , `"subset"` . |

`type` |
One of `"any"` , `"numeric"` , `"double"` .
Using either of latter two coerces the result to have storage mode
`"double"` . |

### Details

`model.extract`

is provided for compatibility with S, which does
not have the more specific functions. It is also useful to extract
e.g. the `etastart`

and `mustart`

components of a
`glm`

fit.

`model.offset`

and `model.response`

are equivalent to
`model.extract(, "offset")`

and `model.extract(, "response")`

respectively. `model.offset`

sums any terms specified by
`offset`

terms in the formula or by `offset`

arguments
in the call producing the model frame: it does check that the offset
is numeric.

`model.weights`

is slightly different from
`model.frame(, "weights")`

in not naming the vector it returns.

### Value

The specified component of the model frame, usually a vector.

### See Also

`model.frame`

, `offset`

### Examples

a <- model.frame(cbind(ncases,ncontrols) ~ agegp+tobgp+alcgp, data=esoph)
model.extract(a, "response")
stopifnot(model.extract(a, "response") == model.response(a))
a <- model.frame(ncases/(ncases+ncontrols) ~ agegp+tobgp+alcgp,
data = esoph, weights = ncases+ncontrols)
model.response(a)
model.extract(a, "weights")
a <- model.frame(cbind(ncases,ncontrols) ~ agegp,
something = tobgp, data = esoph)
names(a)
stopifnot(model.extract(a, "something") == esoph$tobgp)

[Package

*stats* version 2.5.0

Index]