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I am using regular expressions to extract university names. Mainly two patterns are observed.
For this, I have written two patterns as,
regex = re.compile('|'.join([r'[Uu]niversity of (\w+){1,3}',r'(?:\S+\s){1,3}\S*[uU]niversity']))
But in few cases I am not getting proper expected answer. For example,
sentence = "Biology Department University of Vienna"
For this sentence, applying above regular expression, I am getting
"Biology Department University"
which is wrong. I feel, since both patterns will be matched, the second pattern is getting matched and phrase is extracted.
I need to give priority for first pattern, so that "university of something" will be extracted in similar scenario.
can anybody help
474
Chaining regular expressions Regular expressions can be chained together using the pipe character (|). This allows for multiple search options to be acceptable in a single regex string.
sub() method will replace all pattern occurrences in the target string. By setting the count=1 inside a re. sub() we can replace only the first occurrence of a pattern in the target string with another string. Set the count value to the number of replacements you want to perform.
\s* - 0+ whitespaces. = - a literal = (\S*) - Group 1 capturing 0+ chars other than whitespace (or \S+ can be used to match 1 or more chars other than whitespace).
To match a character having special meaning in regex, you need to use a escape sequence prefix with a backslash ( \ ). E.g., \. matches "." ; regex \+ matches "+" ; and regex \( matches "(" . You also need to use regex \\ to match "\" (back-slash).
In general, alternations in regular expressions are evaluated from left to right, so the leftmost alternatives are checked first, giving them priority. You already did that, though - the reason why you still got the match from the right side of the alternation is that that match is possible earlier in the string.
Therefore you need to be more specific and only allow a "Foo University" match only if no of follows. You can use a negative lookahead assertion for this:
regex = re.compile('|'.join([r'university of (\w+){1,3}',
r'(?:\S+\s){1,3}\S*university(?!\s+of\b)']),
flags=re.I)
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