138 lines
3.3 KiB
Cython
138 lines
3.3 KiB
Cython
"""
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The :mod:`sklearn.utils.arrayfuncs` module includes a small collection of auxiliary
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functions that operate on arrays.
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"""
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from cython cimport floating
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from cython.parallel cimport prange
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from libc.math cimport fabs
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from libc.float cimport DBL_MAX, FLT_MAX
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from ._cython_blas cimport _copy, _rotg, _rot
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from ._typedefs cimport float64_t
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ctypedef fused real_numeric:
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short
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int
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long
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long long
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float
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double
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def min_pos(const floating[:] X):
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"""Find the minimum value of an array over positive values.
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Returns the maximum representable value of the input dtype if none of the
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values are positive.
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Parameters
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----------
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X : ndarray of shape (n,)
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Input array.
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Returns
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-------
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min_val : float
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The smallest positive value in the array, or the maximum representable value
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of the input dtype if no positive values are found.
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Examples
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--------
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>>> import numpy as np
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>>> from sklearn.utils.arrayfuncs import min_pos
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>>> X = np.array([0, -1, 2, 3, -4, 5])
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>>> min_pos(X)
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2.0
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"""
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cdef Py_ssize_t i
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cdef floating min_val = FLT_MAX if floating is float else DBL_MAX
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for i in range(X.size):
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if 0. < X[i] < min_val:
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min_val = X[i]
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return min_val
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def _all_with_any_reduction_axis_1(real_numeric[:, :] array, real_numeric value):
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"""Check whether any row contains all values equal to `value`.
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It is equivalent to `np.any(np.all(X == value, axis=1))`, but it avoids to
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materialize the temporary boolean matrices in memory.
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Parameters
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----------
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array: array-like
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The array to be checked.
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value: short, int, long, float, or double
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The value to use for the comparison.
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Returns
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-------
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any_all_equal: bool
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Whether or not any rows contains all values equal to `value`.
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"""
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cdef Py_ssize_t i, j
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for i in range(array.shape[0]):
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for j in range(array.shape[1]):
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if array[i, j] != value:
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break
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else: # no break
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return True
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return False
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# General Cholesky Delete.
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# Remove an element from the cholesky factorization
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# m = columns
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# n = rows
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#
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# TODO: put transpose as an option
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def cholesky_delete(floating[:, :] L, int go_out):
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cdef:
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int n = L.shape[0]
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int m = L.strides[0]
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floating c, s
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floating *L1
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int i
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if floating is float:
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m /= sizeof(float)
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else:
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m /= sizeof(double)
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# delete row go_out
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L1 = &L[0, 0] + (go_out * m)
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for i in range(go_out, n-1):
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_copy(i + 2, L1 + m, 1, L1, 1)
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L1 += m
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L1 = &L[0, 0] + (go_out * m)
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for i in range(go_out, n-1):
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_rotg(L1 + i, L1 + i + 1, &c, &s)
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if L1[i] < 0:
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# Diagonals cannot be negative
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L1[i] = fabs(L1[i])
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c = -c
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s = -s
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L1[i + 1] = 0. # just for cleanup
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L1 += m
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_rot(n - i - 2, L1 + i, m, L1 + i + 1, m, c, s)
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def sum_parallel(const floating [:] array, int n_threads):
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"""Parallel sum, always using float64 internally."""
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cdef:
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float64_t out = 0.
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int i = 0
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for i in prange(
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array.shape[0], schedule='static', nogil=True, num_threads=n_threads
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):
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out += array[i]
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return out
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