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from .common cimport BITSET_INNER_DTYPE_C
from .common cimport BITSET_DTYPE_C
from .common cimport X_DTYPE_C
from .common cimport X_BINNED_DTYPE_C
# A bitset is a data structure used to represent sets of integers in [0, n]. We
# use them to represent sets of features indices (e.g. features that go to the
# left child, or features that are categorical). For familiarity with bitsets
# and bitwise operations:
# https://en.wikipedia.org/wiki/Bit_array
# https://en.wikipedia.org/wiki/Bitwise_operation
cdef inline void init_bitset(BITSET_DTYPE_C bitset) nogil: # OUT
cdef:
unsigned int i
for i in range(8):
bitset[i] = 0
cdef inline void set_bitset(BITSET_DTYPE_C bitset, # OUT
X_BINNED_DTYPE_C val) nogil:
bitset[val // 32] |= (1 << (val % 32))
cdef inline unsigned char in_bitset(BITSET_DTYPE_C bitset,
X_BINNED_DTYPE_C val) nogil:
return (bitset[val // 32] >> (val % 32)) & 1
cpdef inline unsigned char in_bitset_memoryview(const BITSET_INNER_DTYPE_C[:] bitset,
X_BINNED_DTYPE_C val) nogil:
return (bitset[val // 32] >> (val % 32)) & 1
cdef inline unsigned char in_bitset_2d_memoryview(const BITSET_INNER_DTYPE_C [:, :] bitset,
X_BINNED_DTYPE_C val,
unsigned int row) nogil:
# Same as above but works on 2d memory views to avoid the creation of 1d
# memory views. See https://github.com/scikit-learn/scikit-learn/issues/17299
return (bitset[row, val // 32] >> (val % 32)) & 1
cpdef inline void set_bitset_memoryview(BITSET_INNER_DTYPE_C[:] bitset, # OUT
X_BINNED_DTYPE_C val):
bitset[val // 32] |= (1 << (val % 32))
def set_raw_bitset_from_binned_bitset(BITSET_INNER_DTYPE_C[:] raw_bitset, # OUT
BITSET_INNER_DTYPE_C[:] binned_bitset,
X_DTYPE_C[:] categories):
"""Set the raw_bitset from the values of the binned bitset
categories is a mapping from binned category value to raw category value.
"""
cdef:
int binned_cat_value
X_DTYPE_C raw_cat_value
for binned_cat_value, raw_cat_value in enumerate(categories):
if in_bitset_memoryview(binned_bitset, binned_cat_value):
set_bitset_memoryview(raw_bitset, <X_BINNED_DTYPE_C>raw_cat_value)
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