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
No Match

/
/

Test String

Code Generator

Language

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"Instrument Method\s*[=:-]\s*(?<dm>.*)" test_str = ("This data was acquired in Method&Run Control.\n" "The MSD parameters were saved in the msdiag register file.\n" "This msparms.txt file was built using the values from the msdiag register.\n" "Some parameters normally reported under MSData acquisition in Tune \n" "may be missing from this msparms.txt file. You may be able to read these \n" "values from Data Analysis. These items are marked with an asterisk (*).\n" " \n" " \n" " \n" "File : C:\\HPCHEM\\1\\DATA\\FIA.D\n" "Operator : Apps Chemist\n" "Date acquired : Wed Apr 09 17:50:26 1997\n" "Instrument Method : Appsprite2\n" " \n" " \n" "Sample information\n" "----------------------------------\n" "Sample name : 50 ng caffeine\n" "Misc info : 50 ng Caffeine run in condensed mode varying fragmentor\n" " \n" " \n" "MS parameters\n" "----------------------------------\n" "Tune File : C:\\HPCHEM\\1\\1946TUNE\\atunes.tun\n" "Skim1 : Not Applicable\n" "Skim2 : 8.0 V \n" "Ion Energy : 5.0 V \n" "Lens1 : 1.4 V \n" "Lens2 : 27 V \n" "Iris : 350 V \n" "HED : 10000 V \n" "Width Gain : -70 \n" "Width Offset : Variable \n" " Mass : Value \n" " --------------------------\n" " 118.10 : -11 \n" " 622.03 : -14 \n" " 922.01 : -2 \n" " 1521.97 : -8 \n" " 2121.93 : -13 \n" " 2721.89 : -12 \n" " --------------------------\n" "Mass Gain : 4.40 \n" "Mass Offset : Variable \n" " Mass : Value \n" " --------------------------\n" " 118.10 : 0 \n" " 622.03 : 0 \n" " 922.01 : 0 \n" " 1521.97 : 0 \n" " 2121.93 : 0 \n" " 2721.89 : 0 \n" " --------------------------\n" "Quad DC : 0.00 V \n" "Octopole Peak : 300 V \n" "Octopole Knee : 307 Da \n" "Mass Filter : Gaussian \n" "Mass Filter Width : 0.30 Da \n") matches = re.search(regex, test_str) if matches: print ("Match was found at {start}-{end}: {match}".format(start = matches.start(), end = matches.end(), match = matches.group())) for groupNum in range(0, len(matches.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = matches.start(groupNum), end = matches.end(groupNum), group = matches.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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