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Jakub Pokrywka
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README.md
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README.md
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# DJFZ 2021
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# DJFZ 202/home/kuba/Syncthing/przedmioty/2021-01/djfz/djfz-2021/README.md1
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## Zajęcia 1 11.10.2021
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@ -174,3 +174,134 @@ re.search('mam (kota).*(kota|psa)','Ja mam kota. Ala ma psa.').group(1)
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re.search('mam (kota).*(kota|psa)','Ja mam kota. Ala ma psa.').group(2)
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```
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### Przykłady wyrażenia regularne 2 (objaśnienia na laboratoriach)
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#### ^
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```
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re.search('[^0-9][0-9]+[^0-9]', '123-456-789')
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```
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#### cudzysłów
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'' oraz "" - oznaczają to samo w pythonie
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' ala ma psa o imieniu "Burek"'
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" ala ma psa o imieniu 'Burek'"
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' ala ma psa o imieniu \'Burek\''
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" ala ma psa o imieniu \"Burek\""
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#### multiline string
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#### raw string
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przy raw string znaki \ traktowane są jako zwykłe znaki '\'
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chociaż nawet w raw string nadal są escapowane (chociaż wtedy \ pozostają również w stringu bez zmian)
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https://docs.python.org/3/reference/lexical_analysis.html
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dobra praktyka - wszędzie escapować
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```
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'\\'
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print('\\')
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r'\\'
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print(r'\\')
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print("abcd")
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print("ab\cd")
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print(r"ab\cd")
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print("ab\nd")
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print(r"ab\nd")
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print("\"")
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print(r"\"")
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print("\")
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print(r"\")
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re.search('\\', r'a\bc')
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re.search(r'\\', r'a\bc')
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re.search('\\\\', r'a\bc')
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```
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#### RE SUB
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```
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re.sub(pattern, replacement, string)
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re.sub('a','b', 'ala ma kota')
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```
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#### backreferencje:
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```
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re.search(r' \d+ \d+', 'ala ma 41 41 kota')
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re.search(r' \d+ \d+', 'ala ma 41 123 kota')
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re.search(r' (\d+) \1', 'ala ma 41 41 kota')
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re.search(r' (\d+) \1', 'ala ma 41 123 kota')
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```
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#### lookahead ( to sa takie assercje):
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```
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re.search(r'ma kot', 'ala ma kot')
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re.search(r'ma kot(?=[ay])', 'ala ma kot')
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re.search(r'ma kot(?=[ay])', 'ala ma kotka')
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re.search(r'ma kot(?=[ay])', 'ala ma koty')
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re.search(r'ma kot(?=[ay])', 'ala ma kota')
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re.search(r'ma kot(?![ay])', 'ala ma kot')
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re.search(r'ma kot(?![ay])', 'ala ma kotka')
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re.search(r'ma kot(?![ay])', 'ala ma koty')
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re.search(r'ma kot(?![ay])', 'ala ma kota')
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```
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#### named groups
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```
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r = re.search(r'ma (?P<ilepsow>\d+) kotow i (?P<ilekotow>\d+) psow', 'ala ma 100 kotow i 200 psow')
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r.groups()
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r.groups('ilepsow')
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r.groups('ilekotow')
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```
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#### re.split
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```
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('a,b,c,d').split(',')
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re.split(r',', 'a,b,c,d')
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re.split(r'[.,]', 'a,b.c,d')
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```
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#### \w word character
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```
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\w - matchuje Unicod word character , jeżeli flaga ASCII to [a-zA-Z0-9_]
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\w - odwrotne do \W, jezeli flaga ASCI to [^a-zA-Z0-9_]
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re.findall(r'\w+', 'ala ma 3 koty')
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re.findall(r'\W+', 'ala ma 3 koty')
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```
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#### początek albo koniec słowa | word boundary
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```
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re.search(r'\bkot\b', 'Ala ma kota')
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re.search(r'\bkot\b', 'Ala ma kot')
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re.search(r'\bkot\b', 'Ala ma kot.')
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re.search(r'\bkot\b', 'Ala ma kot ')
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re.search(r'\Bot\B', 'Ala ma kot ')
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re.search(r'\Bot\B', 'Ala ma kota ')
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```
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#### MULTILINE
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```
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re.findall(r'^Ma', 'Ma kota Ala\nMa psa Jacek')
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re.findall(r'^Ma', 'Ma kota Ala\nMa psa Jacek', re.MULTILINE)
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```
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#### RE.COMPILE
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64
compile_example.py
Normal file
64
compile_example.py
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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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