regex101: ShortcutLinkInline

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Group key(?P<key>.+?)

.+?any Unicode character, repeated at least once

Non-Capturing Group(?:\s+(?P<settings>.*?))?

?repeats the group contents below at most once:

\s+a Unicode whitespace character, repeated at least once

Group settings(?P<settings>.*?)

.*?any Unicode character, repeated any number of times

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

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

s modifier: single line. Allows a dot to match line terminators

u modifier: unicode. Makes \w, \W, \b, \B, \d, \D, \s, and \S use Unicode semantics (redundant in Python 3)

Search reference

Regular Expression

\[(?P<key>.+?)(?:\s+(?P<settings>.*?))?\]

Test String
New

### The I_Soil System

The I-soil material model is a nonlinear hysteretic soil model that is based on the distributed
element models developed by [!citet](iwan1967on) and [!citet](chiang1994anew). In 1-D, this model takes
the backbone stress-strain curve and divides it into a set of elastic-perfectly plastic curves. The
total stress then is the sum of the stresses from the individual elastic-perfectly plastic curves.

The three dimensional generalization of this model is achieved using von-Mises failure criteria for
each elastic-perfectly plastic curve resulting in an invariant yield surfaces in three-dimensional
stress space like in [fig:yieldsurface] (after [!citet](chiang1994anew)).

Regular Expression

Test StringNew

Test String
New