plot.Gam | R Documentation |

A plot method for GAM objects, which can be used on GLM and LM objects as well. It focuses on terms (main-effects), and produces a suitable plot for terms of different types

```
## S3 method for class 'Gam'
plot(
x,
residuals = NULL,
rugplot = TRUE,
se = FALSE,
scale = 0,
ask = FALSE,
terms = labels.Gam(x),
...
)
## S3 method for class 'Gam'
preplot(object, newdata, terms = labels.Gam(object), ...)
```

`x` |
a |

`residuals` |
if |

`rugplot` |
if |

`se` |
if |

`scale` |
a lower limit for the number of units covered by the
limits on the |

`ask` |
if |

`terms` |
subsets of the terms can be selected |

`...` |
Additonal plotting arguments, not all of which will work (like xlim) |

`object` |
same as |

`newdata` |
if supplied to |

a plot is produced for each of the terms in the object
`x`

. The function currently knows how to plot all
main-effect functions of one or two predictors. So in particular,
interactions are not plotted. An appropriate `x-y`

is produced to
display each of the terms, adorned with residuals, standard-error
curves, and a rugplot, depending on the choice of options. The
form of the plot is different, depending on whether the `x`

-value
for each plot is numeric, a factor, or a matrix.

When `ask=TRUE`

, rather than produce each plot sequentially,
`plot.Gam()`

displays a menu listing all the terms that can be plotted,
as well as switches for all the options.

A `preplot.Gam`

object is a list of precomputed terms. Each such term
(also a `preplot.Gam`

object) is a list with components `x`

,
`y`

and othersâ€”the basic ingredients needed for each term plot. These
are in turn handed to the specialized plotting function `gplot()`

,
which has methods for different classes of the leading `x`

argument. In
particular, a different plot is produced if `x`

is numeric, a category
or factor, a matrix, or a list. Experienced users can extend this range by
creating more `gplot()`

methods for other classes. Graphical
parameters (see `par`

) may also be supplied as arguments to this
function. This function is a method for the generic function `plot()`

for class `"Gam"`

.

It can be invoked by calling `plot(x)`

for an object `x`

of the
appropriate class, or directly by calling `plot.Gam(x)`

regardless of
the class of the object.

Written by Trevor Hastie, following closely the design in the "Generalized Additive Models" chapter (Hastie, 1992) in Chambers and Hastie (1992).

Hastie, T. J. (1992) *Generalized additive models.* Chapter
7 of *Statistical Models in S* eds J. M. Chambers and T. J. Hastie,
Wadsworth & Brooks/Cole.

Hastie, T. and Tibshirani, R. (1990) *Generalized Additive Models.*
London: Chapman and Hall.

`preplot`

, `predict.Gam`

```
data(gam.data)
Gam.object <- gam(y ~ s(x,6) + z,data=gam.data)
plot(Gam.object,se=TRUE)
data(gam.newdata)
preplot(Gam.object,newdata=gam.newdata)
```

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