letterBoundary

Match boundary between letter characters and non-letter characters

Since R2020b

Syntax

pat = letterBoundary

pat = letterBoundary(type)

Description

pat = letterBoundary creates a pattern that matches the start or end of a run of letter characters. letterBoundary can be negated using the ~ operator. When negated, ~letterBoundary matches the boundary between any two characters except at the start or end of a run of letters.

pat = letterBoundary(type) specifies whether to match at the start or end of a run of letters and numbers. type can be 'start', 'end', or 'either' (default).

Examples

Match Boundaries of Letters

Use letterBoundary to divide a string along boundaries between letters and nonletter characters.

Create a pattern that matches any letter boundaries.

txt = "123 abc .?! def 456";
pat = letterBoundary;

Use replace to insert "|" characters at the matched boundaries.

replace(txt,pat,"|")

ans = 
"123 |abc| .?! |def| 456"

Match Start and End Boundaries of Letters

Use the "start" and "end" options for letterBoundary to match the boundary between letters and nonletter characters.

Create a string that contains several different character types. Create a pattern that matches any characters between a "start" boundary for letters and an "end" boundary.

txt = "123 abc .?! def 456";
pat = letterBoundary("start") + wildcardPattern(1,inf) + letterBoundary("end");

Extract the pattern.

boundaries = extract(txt,pat)

boundaries = 2x1 string
    "abc"
    "def"

Negating Boundaries of Letters

Use the ~ operator to negate letterBoundary. This matches boundaries between two characters when both are letters or neither are letters.

Create a string that contains several different character types. Create a pattern that matches a negated letterBoundary.

txt = "123 abc .?!";
pat = ~letterBoundary;

Use replace to insert "|" characters to show where ~letterBoundary matches.

boundaries = replace(txt,pat,"|")

boundaries = 
"|1|2|3| a|b|c |.|?|!|"

Input Arguments

type — Boundary type

'either' (default) | 'start' | 'end'

Boundary type, specified as 'start', 'end', or 'either'.

Data Types: char | string

Output Arguments

pat — Pattern expression

pattern object

Pattern expression, returned as a pattern object.

Extended Capabilities

Thread-Based Environment
Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

Version History

Introduced in R2020b