READ_TREE

Reads the contents of each individual tree within the forest of the random forest model.

Syntax

READ_TREE ( USING PARAMETERS model_name='model‑name'
	      [, tree_id=tree‑id]
	      [, format='format'] )

Parameter Settings

Parameter name Set to…
model_name

Identifies the model that is stored as a result of training, where model‑name conforms to conventions described in Identifiers. It must also be unique among all names of sequences, tables, projections, views, and models within the same schema.
tree_id

The tree identifier, an integer between 0 and n-1, where n is the number of trees in the forest. If you omit this parameter, all trees are returned.
format

Output format of the returned tree, one of the following:

  • tabular: Returns a table with the twelve output columns.
  • graphviz: Returns DOT language source that can be passed to a graphviz tool and render a graphic visualization of the tree.

Privileges

Non-superusers: USAGE privileges on the model

Examples

This example shows how you can use the READ_TREE function with the tabular format.

=> SELECT READ_TREE ( USING PARAMETERS model_name='myRFModel', tree_id=1 ,
format= 'tabular')LIMIT 2;
-[ RECORD 1 ]-------------+-------------------
tree_id                   | 1
node_id                   | 1
node_depth                | 0
is_leaf                   | f
is_categorical_split      | f
split_predictor           | petal_length
split_value               | 1.921875
weighted_information_gain | 0.111242236024845
left_child_id             | 2
right_child_id            | 3
prediction                |
probability/variance      |

-[ RECORD 2 ]-------------+-------------------
tree_id                   | 1
node_id                   | 2
node_depth                | 1
is_leaf                   | t
is_categorical_split      |
split_predictor           |
split_value               |
weighted_information_gain |
left_child_id             |
right_child_id            |
prediction                | setosa
probability/variance      | 1

This example shows how you can use the READ_TREE function with the graphviz format.

=> SELECT READ_TREE ( USING PARAMETERS model_name='myRFModel', tree_id=1 ,
format= 'graphviz')LIMIT 1;

-[ RECORD 1 ]+-------------------------------------------------------------------
---------------------------------------------------------------------------------
tree_id      | 1
tree_digraph | digraph Tree{
1 [label="petal_length < 1.921875 ?", color="blue"];
1 -> 2 [label="yes", color="black"];
1 -> 3 [label="no", color="black"];
2 [label="prediction: setosa, probability: 1", color="red"];
3 [label="petal_length < 4.871875 ?", color="blue"];
3 -> 6 [label="yes", color="black"];
3 -> 7 [label="no", color="black"];
6 [label="prediction: versicolor, probability: 1", color="red"];
7 [label="prediction: virginica, probability: 1", color="red"];
}

See Also