metric_lcs.py

# Copyright (c) 2018 luozhouyang
#
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# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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from .string_distance import MetricStringDistance, NormalizedStringDistance
from .longest_common_subsequence import LongestCommonSubsequence


class MetricLCS(MetricStringDistance, NormalizedStringDistance):

    def __init__(self):
        self.lcs = LongestCommonSubsequence()

    def distance(self, s0, s1):
        if s0 is None:
            raise TypeError("Argument s0 is NoneType.")
        if s1 is None:
            raise TypeError("Argument s1 is NoneType.")
        if s0 == s1:
            return 0.0
        max_len = int(max(len(s0), len(s1)))
        if max_len == 0:
            return 0.0
        return 1.0 - (1.0 * self.lcs.length(s0, s1)) / max_len