Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"(^(?:List\sof\sFigures?|Figures?\sLegends?|Captions?|List)\s*:?(?:(?!^)[^\n]+|(?!\n{4,}|\n\w+\s*\w+\s*:?\s*$)\n|Fig)*)", flags=re.MULTILINE | re.IGNORECASE | re.DOTALL) test_str = ("List of Figures:\n\n" "Figure 1 Kalpakkam study area and locations of borewell and surface water sampling points. Low lying area on the western side is clearly delineated.\n\n" "Figure 2 displays Local meteoric water line (in thick line) of Chennai region (Bhishm Kumar et al., 2010) and Evaporation line (in dashed line). The stable isotope (δD and δ18O) composition of borewell and surface water body samples are plotted to analyse their origin.\n\n" "Not figures:\n\n" "Figure 3 depicts the plot of salinity vs. δD for various borewell and surface water samples. It can be seen that borewell (freshwater) and lake water samples are clustered at the lower range of salinity and δD levels. Similarly, the saline water samples are clustered at the higher range of salinity and δD levels.\n\n" "Figure 4 depicts the plot of salinity vs. δ18O for various borewell and surface water samples. It can be seen that borewell (freshwater) and lake water samples are clustered at the lower range of salinity and δ18O levels. Similarly, the saline water samples are clustered at the higher range of salinity and δ18O levels.\n\n" "Not starting with figure") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html