41 lines
1.3 KiB
Cython
41 lines
1.3 KiB
Cython
# Fast inner loop for DBSCAN.
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# Author: Lars Buitinck
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# License: 3-clause BSD
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from libcpp.vector cimport vector
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from ..utils._typedefs cimport uint8_t, intp_t
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def dbscan_inner(const uint8_t[::1] is_core,
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object[:] neighborhoods,
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intp_t[::1] labels):
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cdef intp_t i, label_num = 0, v
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cdef intp_t[:] neighb
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cdef vector[intp_t] stack
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for i in range(labels.shape[0]):
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if labels[i] != -1 or not is_core[i]:
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continue
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# Depth-first search starting from i, ending at the non-core points.
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# This is very similar to the classic algorithm for computing connected
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# components, the difference being that we label non-core points as
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# part of a cluster (component), but don't expand their neighborhoods.
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while True:
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if labels[i] == -1:
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labels[i] = label_num
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if is_core[i]:
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neighb = neighborhoods[i]
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for i in range(neighb.shape[0]):
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v = neighb[i]
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if labels[v] == -1:
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stack.push_back(v)
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if stack.size() == 0:
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break
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i = stack.back()
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stack.pop_back()
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label_num += 1
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