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"\b(?<=\w)\s{20}", flags=re.MULTILINE) test_str = ("Ateles_geoffroyi GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Ateles_hybridus GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Ateles_fusciceps GATGAGTGTGGCAAGGCCCAAGCGGAAGTGC??????????\n" "Ateles_chamek GATGAGTGTGGCAAGGCCCA?????????????????????\n" "Ateles_paniscus ?????????????????????????????????????????\n" "Brachyteles_arachnoides GATGAGTGTGGCAAGGCCCAAGCGGAAGT????????????\n" "Brachyteles_hypoxanthus GATGAGTGTGGCAAG??????????????????????????\n" "Lagothrix_cana GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Lagothrix_lagotricha GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Alouatta_belzebul ?????????????????????????????????????????\n" "Alouatta_caraya ?????????????????????????????????????????\n" "Alouatta_sara GATGAATGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT\n" "Alouatta_palliata GATGAATGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT\n" "Callicebus_brunneus ?????????????????????????????????????????\n" "Callicebus_moloch GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--G?????\n" "Callicebus_cupreus GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT\n" "Callicebus_caligatus GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT\n" "Callicebus_donacophilus GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT\n" "Callicebus_coimbrai GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Callicebus_personatus GATGAGTGTGGCAAGGCCCAAGCGGAA??????????????\n" "Callicebus_nigrifrons GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Cacajao_melanocephalus GATGAGTGTGGCAAAGCCCA?????????????????????\n" "Cacajao_calvus GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Chiropotes_israelita GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Chiropotes_satanas_chiro ?????????????????????????????????????????\n" "Pithecia_irrorata GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--G?????\n" "Pithecia_pithecia GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT\n" "Tarsius_bancanus ?????????????????????????????????????????\n" "Tarsius_syrichta ?????????????????????????????????????????\n" "Lepilemur_ankaranensis AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Lepilemur_septentrionali AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Lepilemur_dorsalis AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Lepilemur_ruficaudatus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Lepilemur_jamesi AACGAGTGTGGCAAGGCCCAGG???????????????????\n" "Microcebus_murinus_subsp AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Microcebus_murinus_subsp ?????????????????????????????????????????\n" "Mirza_zaza AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Cheirogaleus_medius ?????????????????????????????????????????\n" "Propithecus_verreauxi_co ?????????????????????????????????????????\n" "Propithecus_verreauxi AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Propithecus_tattersalli AACGAGTGTGGCAAGGCCCAGGCTGAAGTTCCG--GTTGCT\n" "Propithecus_diadema AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Propithecus_edwardsi AACGAGTGTGGCAAGGCCCAGGCG?????????????????\n" "Avahi_laniger AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_rufus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_collaris AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_fulvus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_albifrons AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_sanfordi AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_mongoz AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_macaco AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_macaco_flavifron AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_coronatus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Eulemur_rubriventer AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Hapalemur_occidentalis AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Hapalemur_griseus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Lemur_catta AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT\n" "Varecia_variegata_varieg AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Varecia_variegata_rubra AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Daubentonia_madagascarie ?????????????????????????????????????????\n" "Nycticebus_bengalensis AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Nycticebus_coucang AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Nycticebus_pygmaeus AACGAGTATGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Loris_tardigradus AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Arctocebus_calabarensis AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Perodicticus_potto AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Otolemur_garnetti AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Otolemur_crassicaudatus AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT\n" "Galago_moholi ?????????????????????????????????????????\n" "Galago_senegalensis ?????????????????????????????????????????\n" "Galago_thomasi AACGAGTGTGGCAAGGCCCAGGCG?????????????????\n" "Galeopterus_variegatus GATGAGTGTGGCAAGGCCCAAGCAGAAGTTCCG--G?????\n" "Cynocephalus_volans GATGAGTGTGGCAAGGCCCAAGCAGAAGTCCCG--GTTGCT\n" "Tupaia_glis ?????????????????????????????????????????\n" "Tupaia_minor ?????????????????????????????????????????\n" "rabbit_rabbit_rabbit ?????????????????????????????????????????\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