adv_lesson1

Lesson 1 - Regular Expressions

Ch2-3 Regex Basics

• Basic syntax
  • re.match(query, search_text)
• Escape character \
• Any character - wild card .
  • Matches any character
• Set of characters [Aa]
  • Matches A and a
• Do not match a set [^Aa]
  • Doesn't match A and a
• Range [A-z]
  • Matches all capital and lowercase letters
• Or a|b
  • Matches a or b
• Kleene star a*
  • Matches zero or more a characters
• Kleene plus a+
  • Matches one or more a characters
• Optional some?
  • Matches both som and some
• Bounded repetitions ba{1,3}
  • Matches both ba, baa, baa
• Grouping ()

Ch4 Boundaries

• search() search anywhere in the string
  • Add ^ marks the start of the sentence
  • Add $ marks the end of the sentence
  • Add \b to signify the end of a word
  • Special characters
    • \d digits
    • \D non-digits
    • \s all white spaces
    • \S all non-white spaces
    • \w a word
    • \W all non-words

Ch6 Patterns

• re.finditer finds multiple
• Pre-compile to object
  • re.compile
• Non-greedy
  • Add an extra ?

Ch7 Groups

• match.groups() retrieves the values of the group
• P<name> assigns a name to the group
  • Retrieved by match.group("name")
• Non-capture groups are specified by (?: )
• Backreferences \\1 refers the first group that was captured
• Find and replace .sub(ptr, rplc, str)
• Split by .split(ptr, str)