regex101: Python Match Workspace

^start of line

Group 1(\d+(?:-\d+)?\s*(M{0,4}(?:C[MD]|D?C{0,3})(?:X[CL]|L?X{0,3})(?:I[XV]|V?I{0,3})))

\d+a Unicode decimal digit, repeated at least once

Non-Capturing Group(?:-\d+)?

?repeats the group contents below at most once:

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\d+a Unicode decimal digit, repeated at least once

\s*a Unicode whitespace character, repeated any number of times

Group 2(M{0,4}(?:C[MD]|D?C{0,3})(?:X[CL]|L?X{0,3})(?:I[XV]|V?I{0,3}))

M{0,4}the literal M (77₁₀ / 115₈ / 4D₁₆) (case sensitive), repeated between 0 and 4 times

Non-Capturing Group(?:C[MD]|D?C{0,3})

1st AlternativeC[MD]

Cthe literal C (67₁₀ / 103₈ / 43₁₆) (case sensitive)

Character Class[MD]

Mthe literal M (77₁₀ / 115₈ / 4D₁₆) (case sensitive)

Dthe literal D (68₁₀ / 104₈ / 44₁₆) (case sensitive)

2nd AlternativeD?C{0,3}

D?optionally matches the literal D (68₁₀ / 104₈ / 44₁₆) (case sensitive)

C{0,3}the literal C (67₁₀ / 103₈ / 43₁₆) (case sensitive), repeated between 0 and 3 times

Non-Capturing Group(?:X[CL]|L?X{0,3})

1st AlternativeX[CL]

Xthe literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive)

Character Class[CL]

Cthe literal C (67₁₀ / 103₈ / 43₁₆) (case sensitive)

Lthe literal L (76₁₀ / 114₈ / 4C₁₆) (case sensitive)

2nd AlternativeL?X{0,3}

L?optionally matches the literal L (76₁₀ / 114₈ / 4C₁₆) (case sensitive)

X{0,3}the literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive), repeated between 0 and 3 times

Non-Capturing Group(?:I[XV]|V?I{0,3})

1st AlternativeI[XV]

Ithe literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive)

Character Class[XV]

Xthe literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive)

Vthe literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

2nd AlternativeV?I{0,3}

V?optionally matches the literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

I{0,3}the literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive), repeated between 0 and 3 times

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\s*a Unicode whitespace character, repeated any number of times

Group 3(.*)

.*any Unicode character (except for line terminators), repeated any number of times

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

^(\d+(?:-\d+)?\s*(M{0,4}(?:C[MD]|D?C{0,3})(?:X[CL]|L?X{0,3})(?:I[XV]|V?I{0,3})))\.\s*(.*)

New

05-21 I. Don Quixote
21-20 IV. Macbeth
10-12 ML. To Kill a Mockingbird
12 V. Invisible Man

Regular Expressions 101

Regular Expression

Substitution