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'SRR([0-9]+)([\.])([0-9]+)([\s]+)([A-Z]+)', flags=re.MULTILINE) test_str = (" sequence_id cdr3_aa\n" "0 SRR11610498.829751 AKDLGPDAGYTVFNDYFDN\n" "1 SRR11610498.853725 AKDLGPDAGYTVFNDYFDN\n" "2 SRR11610498.856922 AKDLGPDAGYTVFNHYFDN\n" "3 SRR11610498.861591 AKDLGPDAGYTVFNDYFDN\n" "4 SRR11610498.909314 AKDLGPDAGYTVFNDYFDN\n" "5 SRR11610498.915768 AKDLGPDAGYTVFNDYFDN\n" "6 SRR11610498.922245 ARGGLVVVDSFDY\n" "7 SRR11610498.1017490 ASDLSYASSWLHYFDV\n" "8 SRR11610498.1022079 ARLRFDNGALYFDY\n" "9 SRR11610498.1037667 ASSAPPSGFNWFDP\n" "10 SRR11610498.1111232 AKGPQIVATTTDNLEV\n" "11 SRR11610498.1183596 AKDLGPDAGYTVFNDYFDN \n\n\n\n") 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