extractBetween — Extract substrings between boundary markers in MATLAB and RunMat.

extractBetween(text, start, stop) returns text between two boundary markers. Numeric positions accept single, double, and all eight integer classes as one-based structural controls.

Syntax

newText = extractBetween(str, start, end)
newText = extractBetween(str, start, end, Name, Value, ...)

Inputs

Returns

Errors

How extractBetween works

• Documented text input is a string array, character vector, or cell array of character vectors. String input returns string output; character-vector and cellstr input return cell arrays of character vectors.
• Boundary inputs can be text or numeric positions. Both boundaries in a call must use the same kind of input; mixing text and numeric markers raises a size/type error.
• Scalar boundaries apply to every text element. Nonscalar boundaries must have exactly the same shape as the text input in strict compatibility mode; broader implicit broadcasting is a RunMat extension.
• The 'Boundaries' name-value pair controls inclusivity. Text markers default to exclusive extraction, while numeric positions default to inclusive behaviour. Values are case-insensitive and must be 'exclusive' or 'inclusive'.
• Missing string scalars propagate: if the text, start marker, or end marker is <missing>, the result is also <missing>.
• When the start or end boundary cannot be located, extractBetween returns an empty string (or an appropriately padded empty row for character arrays).
• Numeric positions use 1-based indexing and are read directly from native single, double, or integer storage. Inputs must be positive integers; stop positions beyond the text length are clamped by the current implementation.
• Row-wise character matrices, cells containing string scalars, and resident numeric positions are separately declared RunMat extensions. Integer, logical, and complex text inputs reject before provider access.

Does RunMat run extractBetween on the GPU?

Text manipulation executes on the CPU. RunMat extension mode can gather resident numeric position controls and leaves results on the host. No Accelerate provider hooks are registered, and numeric resident text is rejected before provider access.

Examples

Extract text between words in a string

txt = "RunMat accelerates MATLAB workloads";
segment = extractBetween(txt, "RunMat ", " workloads")

Expected output:

segment = "accelerates MATLAB"

Include boundary markers with the 'Boundaries' option

path = "snapshots/run/fusion.mat";
withMarkers = extractBetween(path, "snapshots/", ".mat", "Boundaries", "inclusive")

Expected output:

withMarkers = "snapshots/run/fusion.mat"

Use numeric positions for 1-based indexing

name = "Accelerator";
middle = extractBetween(name, 3, 7)

Expected output:

middle = "celer"

Apply scalar text markers to each element of a string array

files = ["runmat_accel.rs", "runmat_gc.rs"; "runmat_plot.rs", "runmat_cli.rs"];
stems = extractBetween(files, "runmat_", ".rs")

Expected output:

stems = 2×2 string
    "accel"    "gc"
    "plot"     "cli"

Extracting text row by row from a character matrix

chars = char("Device<GPU>", "Planner<Fusion>");
tokens = extractBetween(chars, "<", ">")

Expected output:

tokens =

  2×6 char array

    "GPU   "
    "Fusion"

Extracting text from mixed cell contents

C = {'<missing>', 'A[B]C'; "Planner <Fusion>", "Device<GPU>"};
out = extractBetween(C, "<", ">")

Expected output:

out =
  2×2 cell array
    {'<missing>'}    {'B'}
    {"Fusion"}       {"GPU"}

Handle missing strings without throwing errors

txt = ["<missing>", "Planner<GPU>"];
tokens = extractBetween(txt, "<", ">")

Expected output:

tokens = 1×2 string
    "<missing>"    "GPU"

Using extractBetween with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how extractBetween changes the result.

FAQ

Related Strings functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how extractBetween is executed, line by line, in Rust.

• View the source for extractBetween in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

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