Causal trees bootstrapping and max_leaf_nodes fixes with minor upda…

…te (#583)

* Add bootstrap fix for causal forest fit
* Black reformat
* Fix max_leaf_nodes behaviour with BestFirstCausalTreeBuilder
* Add penalty for treatment and control samples distribution
* Add treatment and control info to tree builders
* Manage criterias public variables via BaseCausalDecisionTree
* Add groups info to causal tree plot
* Update CausalTreRegressor and CausalRandomForestRegressor interfaces
* Update causal trees notebooks in examples
* Black code reformat
* Update causal trees tests
* Remove Literal for python=3.7 support
* Fix setup_requires

causalml/inference/tree/__init__.py

@@ -1,4 +1,5 @@
-from .causal.causaltree import CausalTreeRegressor, CausalRandomForestRegressor
+from .causal.causaltree import CausalTreeRegressor
+from .causal.causalforest import CausalRandomForestRegressor
 from .plot import uplift_tree_string, uplift_tree_plot, plot_dist_tree_leaves_values
 from .uplift import DecisionTree, UpliftTreeClassifier, UpliftRandomForestClassifier
 from .utils import (

causalml/inference/tree/causal/_builder.pxd

@@ -0,0 +1,27 @@
+# cython: cdivision=True
+# cython: boundscheck=False
+# cython: wraparound=False
+# cython: language_level=3
+# cython: linetrace=True
+
+from sklearn.tree._tree cimport Node, Tree, TreeBuilder
+from sklearn.tree._tree cimport Splitter, SplitRecord
+from sklearn.tree._utils cimport StackRecord, Stack
+from sklearn.tree._utils cimport PriorityHeapRecord, PriorityHeap
+from sklearn.tree._tree cimport SIZE_t, DOUBLE_t
+
+
+cdef struct FrontierRecord:
+    # Record of information of a Node, the frontier for a split. Those records are
+    # maintained in a heap to access the Node with the best improvement in impurity,
+    # allowing growing trees greedily on this improvement.
+    SIZE_t node_id
+    SIZE_t start
+    SIZE_t end
+    SIZE_t pos
+    SIZE_t depth
+    bint is_leaf
+    double impurity
+    double impurity_left
+    double impurity_right
+    double improvement