View source: R/xgb.plot.deepness.R

xgb.ggplot.deepness | R Documentation |

Visualizes distributions related to depth of tree leafs.
`xgb.plot.deepness`

uses base R graphics, while `xgb.ggplot.deepness`

uses the ggplot backend.

```
xgb.ggplot.deepness(
model = NULL,
which = c("2x1", "max.depth", "med.depth", "med.weight")
)
xgb.plot.deepness(
model = NULL,
which = c("2x1", "max.depth", "med.depth", "med.weight"),
plot = TRUE,
...
)
```

`model` |
either an |

`which` |
which distribution to plot (see details). |

`plot` |
(base R barplot) whether a barplot should be produced. If FALSE, only a data.table is returned. |

`...` |
other parameters passed to |

When `which="2x1"`

, two distributions with respect to the leaf depth
are plotted on top of each other:

the distribution of the number of leafs in a tree model at a certain depth;

the distribution of average weighted number of observations ("cover") ending up in leafs at certain depth.

Those could be helpful in determining sensible ranges of the `max_depth`

and `min_child_weight`

parameters.

When `which="max.depth"`

or `which="med.depth"`

, plots of either maximum or median depth
per tree with respect to tree number are created. And `which="med.weight"`

allows to see how
a tree's median absolute leaf weight changes through the iterations.

This function was inspired by the blog post https://github.com/aysent/random-forest-leaf-visualization.

Other than producing plots (when `plot=TRUE`

), the `xgb.plot.deepness`

function
silently returns a processed data.table where each row corresponds to a terminal leaf in a tree model,
and contains information about leaf's depth, cover, and weight (which is used in calculating predictions).

The `xgb.ggplot.deepness`

silently returns either a list of two ggplot graphs when `which="2x1"`

or a single ggplot graph for the other `which`

options.

`xgb.train`

, `xgb.model.dt.tree`

.

```
data(agaricus.train, package='xgboost')
## Keep the number of threads to 2 for examples
nthread <- 2
data.table::setDTthreads(nthread)
## Change max_depth to a higher number to get a more significant result
bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 6,
eta = 0.1, nthread = nthread, nrounds = 50, objective = "binary:logistic",
subsample = 0.5, min_child_weight = 2)
xgb.plot.deepness(bst)
xgb.ggplot.deepness(bst)
xgb.plot.deepness(bst, which='max.depth', pch=16, col=rgb(0,0,1,0.3), cex=2)
xgb.plot.deepness(bst, which='med.weight', pch=16, col=rgb(0,0,1,0.3), cex=2)
```

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