1cimport numpy as np
2from libc.math cimport sqrt, exp
3
4from ..utils._typedefs cimport DTYPE_t, ITYPE_t
5
6######################################################################
7# Inline distance functions
8#
9#  We use these for the default (euclidean) case so that they can be
10#  inlined.  This leads to faster computation for the most common case
11cdef inline DTYPE_t euclidean_dist(const DTYPE_t* x1, const DTYPE_t* x2,
12                                   ITYPE_t size) nogil except -1:
13    cdef DTYPE_t tmp, d=0
14    cdef np.intp_t j
15    for j in range(size):
16        tmp = x1[j] - x2[j]
17        d += tmp * tmp
18    return sqrt(d)
19
20
21cdef inline DTYPE_t euclidean_rdist(const DTYPE_t* x1, const DTYPE_t* x2,
22                                    ITYPE_t size) nogil except -1:
23    cdef DTYPE_t tmp, d=0
24    cdef np.intp_t j
25    for j in range(size):
26        tmp = x1[j] - x2[j]
27        d += tmp * tmp
28    return d
29
30
31cdef inline DTYPE_t euclidean_dist_to_rdist(const DTYPE_t dist) nogil except -1:
32    return dist * dist
33
34
35cdef inline DTYPE_t euclidean_rdist_to_dist(const DTYPE_t dist) nogil except -1:
36    return sqrt(dist)
37
38
39######################################################################
40# DistanceMetric base class
41cdef class DistanceMetric:
42    # The following attributes are required for a few of the subclasses.
43    # we must define them here so that cython's limited polymorphism will work.
44    # Because we don't expect to instantiate a lot of these objects, the
45    # extra memory overhead of this setup should not be an issue.
46    cdef DTYPE_t p
47    cdef DTYPE_t[::1] vec
48    cdef DTYPE_t[:, ::1] mat
49    cdef ITYPE_t size
50    cdef object func
51    cdef object kwargs
52
53    cdef DTYPE_t dist(self, const DTYPE_t* x1, const DTYPE_t* x2,
54                      ITYPE_t size) nogil except -1
55
56    cdef DTYPE_t rdist(self, const DTYPE_t* x1, const DTYPE_t* x2,
57                       ITYPE_t size) nogil except -1
58
59    cdef int pdist(self, const DTYPE_t[:, ::1] X, DTYPE_t[:, ::1] D) except -1
60
61    cdef int cdist(self, const DTYPE_t[:, ::1] X, const DTYPE_t[:, ::1] Y,
62                   DTYPE_t[:, ::1] D) except -1
63
64    cdef DTYPE_t _rdist_to_dist(self, DTYPE_t rdist) nogil except -1
65
66    cdef DTYPE_t _dist_to_rdist(self, DTYPE_t dist) nogil except -1
67