105 lines
4.5 KiB
Cython
105 lines
4.5 KiB
Cython
# Authors: Gilles Louppe <g.louppe@gmail.com>
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# Peter Prettenhofer <peter.prettenhofer@gmail.com>
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# Brian Holt <bdholt1@gmail.com>
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# Joel Nothman <joel.nothman@gmail.com>
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# Arnaud Joly <arnaud.v.joly@gmail.com>
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# Jacob Schreiber <jmschreiber91@gmail.com>
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# Nelson Liu <nelson@nelsonliu.me>
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#
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# License: BSD 3 clause
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# See _tree.pyx for details.
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import numpy as np
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cimport numpy as np
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ctypedef np.npy_float32 DTYPE_t # Type of X
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ctypedef np.npy_float64 DOUBLE_t # Type of y, sample_weight
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ctypedef np.npy_intp SIZE_t # Type for indices and counters
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ctypedef np.npy_int32 INT32_t # Signed 32 bit integer
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ctypedef np.npy_uint32 UINT32_t # Unsigned 32 bit integer
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from ._splitter cimport Splitter
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from ._splitter cimport SplitRecord
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cdef struct Node:
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# Base storage structure for the nodes in a Tree object
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SIZE_t left_child # id of the left child of the node
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SIZE_t right_child # id of the right child of the node
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SIZE_t feature # Feature used for splitting the node
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DOUBLE_t threshold # Threshold value at the node
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DOUBLE_t impurity # Impurity of the node (i.e., the value of the criterion)
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SIZE_t n_node_samples # Number of samples at the node
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DOUBLE_t weighted_n_node_samples # Weighted number of samples at the node
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cdef class Tree:
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# The Tree object is a binary tree structure constructed by the
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# TreeBuilder. The tree structure is used for predictions and
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# feature importances.
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# Input/Output layout
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cdef public SIZE_t n_features # Number of features in X
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cdef SIZE_t* n_classes # Number of classes in y[:, k]
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cdef public SIZE_t n_outputs # Number of outputs in y
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cdef public SIZE_t max_n_classes # max(n_classes)
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# Inner structures: values are stored separately from node structure,
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# since size is determined at runtime.
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cdef public SIZE_t max_depth # Max depth of the tree
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cdef public SIZE_t node_count # Counter for node IDs
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cdef public SIZE_t capacity # Capacity of tree, in terms of nodes
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cdef Node* nodes # Array of nodes
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cdef double* value # (capacity, n_outputs, max_n_classes) array of values
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cdef SIZE_t value_stride # = n_outputs * max_n_classes
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# Methods
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cdef SIZE_t _add_node(self, SIZE_t parent, bint is_left, bint is_leaf,
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SIZE_t feature, double threshold, double impurity,
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SIZE_t n_node_samples,
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double weighted_n_samples) nogil except -1
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cdef int _resize(self, SIZE_t capacity) nogil except -1
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cdef int _resize_c(self, SIZE_t capacity=*) nogil except -1
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cdef np.ndarray _get_value_ndarray(self)
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cdef np.ndarray _get_node_ndarray(self)
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cpdef np.ndarray predict(self, object X)
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cpdef np.ndarray apply(self, object X)
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cdef np.ndarray _apply_dense(self, object X)
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cdef np.ndarray _apply_sparse_csr(self, object X)
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cpdef object decision_path(self, object X)
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cdef object _decision_path_dense(self, object X)
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cdef object _decision_path_sparse_csr(self, object X)
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cpdef compute_feature_importances(self, normalize=*)
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# =============================================================================
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# Tree builder
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# =============================================================================
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cdef class TreeBuilder:
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# The TreeBuilder recursively builds a Tree object from training samples,
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# using a Splitter object for splitting internal nodes and assigning
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# values to leaves.
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#
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# This class controls the various stopping criteria and the node splitting
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# evaluation order, e.g. depth-first or best-first.
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cdef Splitter splitter # Splitting algorithm
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cdef SIZE_t min_samples_split # Minimum number of samples in an internal node
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cdef SIZE_t min_samples_leaf # Minimum number of samples in a leaf
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cdef double min_weight_leaf # Minimum weight in a leaf
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cdef SIZE_t max_depth # Maximal tree depth
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cdef double min_impurity_split
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cdef double min_impurity_decrease # Impurity threshold for early stopping
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cpdef build(self, Tree tree, object X, np.ndarray y,
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np.ndarray sample_weight=*,
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np.ndarray X_idx_sorted=*)
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cdef _check_input(self, object X, np.ndarray y, np.ndarray sample_weight)
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