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88 lines
3.2 KiB
88 lines
3.2 KiB
5 years ago
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# -*- coding: utf-8 -*-
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import logging
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import math
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import numpy as np
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from .sklearn_shim import TransformerMixin
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logging.basicConfig(level=logging.INFO)
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logger = logging.getLogger(__name__)
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class FailedToFindAlignmentException(Exception):
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pass
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class FFTAligner(TransformerMixin):
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def __init__(self):
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self.best_offset_ = None
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self.best_score_ = None
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self.get_score_ = False
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def fit(self, refstring, substring, get_score=False):
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refstring, substring = [
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list(map(int, s))
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if isinstance(s, str) else s
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for s in [refstring, substring]
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]
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refstring, substring = map(
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lambda s: 2 * np.array(s).astype(float) - 1, [refstring, substring])
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total_bits = math.log(len(substring) + len(refstring), 2)
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total_length = int(2 ** math.ceil(total_bits))
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extra_zeros = total_length - len(substring) - len(refstring)
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subft = np.fft.fft(np.append(np.zeros(extra_zeros + len(refstring)), substring))
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refft = np.fft.fft(np.flip(np.append(refstring, np.zeros(len(substring) + extra_zeros)), 0))
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convolve = np.real(np.fft.ifft(subft * refft))
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best_idx = np.argmax(convolve)
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self.best_offset_ = len(convolve) - 1 - best_idx - len(substring)
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self.best_score_ = convolve[best_idx]
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self.get_score_ = get_score
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return self
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def transform(self, *_):
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if self.get_score_:
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return self.best_score_, self.best_offset_
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else:
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return self.best_offset_
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class MaxScoreAligner(TransformerMixin):
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def __init__(self, base_aligner, sample_rate=None, max_offset_seconds=None):
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if isinstance(base_aligner, type):
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self.base_aligner = base_aligner()
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else:
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self.base_aligner = base_aligner
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self.max_offset_seconds = max_offset_seconds
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if sample_rate is None or max_offset_seconds is None:
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self.max_offset_samples = None
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else:
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self.max_offset_samples = abs(max_offset_seconds * sample_rate)
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self._scores = []
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def fit(self, refstring, subpipes):
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if not isinstance(subpipes, list):
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subpipes = [subpipes]
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for subpipe in subpipes:
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if hasattr(subpipe, 'transform'):
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substring = subpipe.transform(None)
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else:
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substring = subpipe
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self._scores.append((
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self.base_aligner.fit_transform(
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refstring, substring, get_score=True
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),
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subpipe
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))
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return self
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def transform(self, *_):
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scores = self._scores
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if self.max_offset_samples is not None:
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scores = list(filter(lambda s: abs(s[0][1]) <= self.max_offset_samples, scores))
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if len(scores) == 0:
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raise FailedToFindAlignmentException('Synchronization failed; consider passing '
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'--max-offset-seconds with a number larger than '
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'{}'.format(self.max_offset_seconds))
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(score, offset), subpipe = max(scores, key=lambda x: x[0][0])
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return offset, subpipe
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