# plot_gbm

##### Plot a gbm model

Plot a `gbm`

model showing the training and other
error curves.

##### Usage

```
plot_gbm(object=stop("no 'object' argument"),
smooth = c(0, 0, 0, 1),
col = c(1, 2, 3, 4), ylim = "auto",
legend.x = NULL, legend.y = NULL, legend.cex = .8,
grid.col = NA,
n.trees = NA, col.n.trees ="darkgray",
...)
```

##### Arguments

- object
The

`gbm`

model.- smooth
Four-element vector specifying if smoothing should be applied to the train, test, CV, and OOB curves respectively. When smoothing is specified, a smoothed curve is plotted and the minimum is calculated from the smoothed curve. The default is c(0, 0, 0, 1) meaning apply smoothing only to the OOB curve (same as

`gbm.perf`

). Note that`smooth=1`

(which gets recyled to`c(1,1,1,1)`

) will smooth all the curves.- col
Four-element vector specifying the colors for the train, test, CV, and OOB curves respectively. The default is

`c(1, 2, 3, 4)`

. Use a color of`0`

to remove the corresponding curve, e.g.`col=c(1,2,3,0)`

to not display the OOB curve. If`col=0`

(which gets recycled to`c(0,0,0,0)`

) nothing will be plotted, but`plot_gbm`

will return the number-of-trees at the minima as usual (as described in the Value section below).- ylim
The default

`ylim="auto"`

shows more detail around the minima. Use`ylim=NULL`

for the full vertical range of the curves. Else specify`ylim`

as usual.- legend.x
The x position of the legend. The default positions the legend automatically. Use

`legend.x=NA`

for no legend. See the`x`

and`y`

arguments of`xy.coords`

for other options, for example`legend.x="topright"`

.- legend.y
The y position of the legend.

- legend.cex
The legend

`cex`

(the default is`0.8`

).- grid.col
Default

`NA`

. Color of the optional grid, for example`grid.col=1`

.- n.trees
For use by

`plotres`

. The x position of the gray vertical line indicating the`n.trees`

passed by`plotres`

to`predict.gbm`

to calculate the residuals. Plotres defaults to all trees.- col.n.trees
For use by

`plotres`

. Color of the vertical line showing the`n.trees`

argument. Default is`"darkgray"`

.- …
Dot arguments are passed internally to

`plot.default`

.

##### Value

This function returns a four-element vector specifying the number of trees at the train, test, CV, and OOB minima respectively.

The minima are calculated after smoothing as specified by this
function's `smooth`

argument.
By default, only the OOB curve is smoothed.
The smoothing algorithm for the OOB curve differs slightly
from `gbm.perf`

, so can give a slightly
different number of trees.

##### Note

**The OOB curve**

The OOB curve is artificially rescaled to force it into the plot. See Chapter 7 in the plotres vignette.

**Interaction with plotres**

When invoking this function via `plotres`

, prefix any
argument of `plotres`

with `w1.`

to tell `plotres`

to
pass the argument to this function.
For example give `w1.ylim=c(0,10)`

to `plotres`

(plain
`ylim=c(0,10)`

in this context gets passed to the residual
plots).

**Acknowledgments**

This function is derived from code in the `gbm`

package authored by Greg Ridgeway and others.

##### See Also

Chapter 7 in plotres vignette discusses this function.

##### Examples

```
# NOT RUN {
if (require(gbm)) {
n <- 100 # toy model for quick demo
x1 <- 3 * runif(n)
x2 <- 3 * runif(n)
x3 <- sample(1:4, n, replace=TRUE)
y <- x1 + x2 + x3 + rnorm(n, 0, .3)
data <- data.frame(y=y, x1=x1, x2=x2, x3=x3)
mod <- gbm(y~., data=data, distribution="gaussian",
n.trees=300, shrinkage=.1, interaction.depth=3,
train.fraction=.8, verbose=FALSE)
plot_gbm(mod)
# plotres(mod) # plot residuals
# plotmo(mod) # plot regression surfaces
}
# }
```

*Documentation reproduced from package plotmo, version 3.4.0, License: GPL-3*