65 lines
1.8 KiB
Python
65 lines
1.8 KiB
Python
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# fron https://stackoverflow.com/questions/452104/is-it-worth-using-pythons-re-compile#comment108948583_452104
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import re
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import time
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def setup(N=1000):
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# Patterns 'a.*a', 'a.*b', ..., 'z.*z'
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patterns = [chr(i) + '.*' + chr(j)
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for i in range(ord('a'), ord('z') + 1)
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for j in range(ord('a'), ord('z') + 1)]
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# If this assertion below fails, just add more (distinct) patterns.
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# assert(re._MAXCACHE < len(patterns))
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# N strings. Increase N for larger effect.
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strings = ['abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz'] * N
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return (patterns, strings)
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def without_compile():
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print('Without re.compile:')
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patterns, strings = setup()
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print('searching')
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count = 0
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for s in strings:
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for pat in patterns:
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count += bool(re.search(pat, s))
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return count
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def without_compile_cache_friendly():
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print('Without re.compile, cache-friendly order:')
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patterns, strings = setup()
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print('searching')
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count = 0
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for pat in patterns:
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for s in strings:
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count += bool(re.search(pat, s))
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return count
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def with_compile():
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print('With re.compile:')
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patterns, strings = setup()
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print('compiling')
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compiled = [re.compile(pattern) for pattern in patterns]
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print('searching')
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count = 0
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for s in strings:
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for regex in compiled:
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count += bool(regex.search(s))
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return count
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start = time.time()
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print(with_compile())
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d1 = time.time() - start
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print(f'-- That took {d1:.2f} seconds.\n')
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start = time.time()
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print(without_compile_cache_friendly())
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d2 = time.time() - start
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print(f'-- That took {d2:.2f} seconds.\n')
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start = time.time()
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print(without_compile())
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d3 = time.time() - start
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print(f'-- That took {d3:.2f} seconds.\n')
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print(f'Ratio: {d3/d1:.2f}')
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