regex101: Python Match Workspace

Explanation

Pro

Negative Lookbehind(?<!\S)

\Sany character that is not Unicode whitespace

Non-Capturing Group(?:(\d+\.\d+)x(\d+\.\d+)x(\d+\.\d+) [cm]m|(\d(?:\.\d+)?))

1st Alternative(\d+\.\d+)x(\d+\.\d+)x(\d+\.\d+) [cm]m

Group 1(\d+\.\d+)

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

Group 2(\d+\.\d+)

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

Group 3(\d+\.\d+)

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

the literal (32₁₀ / 40₈ / 20₁₆)

Character Class[cm]

cthe literal c (99₁₀ / 143₈ / 63₁₆) (case sensitive)

mthe literal m (109₁₀ / 155₈ / 6D₁₆) (case sensitive)

2nd Alternative(\d(?:\.\d+)?)

Group 4(\d(?:\.\d+)?)

\da Unicode decimal digit

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

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

Negative Lookahead(?!\S)

\Sany character that is not Unicode whitespace

Global pattern flags

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

Quick Reference

25 tokens

Regular Expression

(?<!\S)(?:(\d+\.\d+)x(\d+\.\d+)x(\d+\.\d+) [cm]m|(\d(?:\.\d+)?))(?!\S)

New

The study reveals a speculated nodule with pleural tagging at anterior basal segment of LLL, measured 1.9x1.4x2.0 cm in size
Other two ill defined, small ground glass lesions measured 4.0 mm and 3 mm in size, respectively.

Substitution

The study reveals a speculated nodule with pleural tagging at anterior basal segment of LLL, measured 1.9x1.4x2.0 cm in size
Other two ill defined, small ground glass lesions measured 4.0 mm and 3 mm in size, respectively.