RunMat
GitHub

View all functions

CategoryStrings: Transform

What does the erase function do in MATLAB / RunMat?

erase(text, pattern) removes every occurrence of pattern from text. The builtin accepts string scalars, string arrays, character arrays, and cell arrays of character vectors or string scalars, mirroring MATLAB behaviour. When pattern is an array, erase removes every occurrence of each pattern entry; the text and pattern arguments do not need to be the same size.

How does the erase function behave in MATLAB / RunMat?

  • String inputs stay as strings. Missing string scalars (<missing>) propagate unchanged.
  • String arrays preserve their size and orientation. Each element has every supplied pattern removed.
  • Character arrays are processed row by row. Rows shrink as characters are removed and are padded with spaces so the result remains a rectangular char array.
  • Cell arrays must contain string scalars or character vectors. The result is a cell array with the same shape whose elements reflect the removed substrings.
  • The pattern input can be a string scalar, string array, character array, or cell array of character vectors/string scalars. Provide either a scalar pattern or a list; an empty list leaves text unchanged.
  • Pattern values are treated literally—no regular expressions are used. Use replace or the regex builtins for pattern-based removal.

erase Function GPU Execution Behaviour

erase executes on the CPU. When any argument is GPU-resident, RunMat gathers it to host memory before removing substrings. Outputs are returned on the host as well. Providers do not need to implement device kernels for this builtin, and the fusion planner treats it as a sink to avoid keeping text on the GPU.

GPU residency in RunMat (Do I need gpuArray?)

No. erase automatically gathers GPU inputs and produces host results. You never need to move text to or from the GPU manually for this builtin, and gpuArray inputs are handled transparently.

Examples of using the erase function in MATLAB / RunMat

Remove a single word from a string scalar

txt = "RunMat accelerates MATLAB code";
clean = erase(txt, "accelerates ");

Expected output:

clean = "RunMat MATLAB code"

Remove multiple substrings from each element of a string array

labels = ["GPU pipeline"; "CPU pipeline"];
result = erase(labels, ["GPU ", "CPU "]);

Expected output:

result = 2×1 string
    "pipeline"
    "pipeline"

Erase characters from a character array while preserving padding

chars = char("workspace", "snapshots");
trimmed = erase(chars, "s");

Expected output:

trimmed =

  2×8 char array

    'workpace'
    'napshot '

Remove substrings from a cell array of text

C = {'Kernel Planner', "GPU Fusion"};
out = erase(C, ["Kernel ", "GPU "]);

Expected output:

out = 1×2 cell array
    {'Planner'}    {"Fusion"}

Provide an empty pattern list to leave the text unchanged

data = ["alpha", "beta"];
unchanged = erase(data, string.empty);

Expected output:

unchanged = 1×2 string
    "alpha"    "beta"

Remove delimiters before splitting text

path = "runmat/bin:runmat/lib";
clean = erase(path, ":");
parts = split(clean, "runmat/");

Expected output:

clean = "runmat/binrunmat/lib"
parts = 1×3 string
    ""    "bin"    "lib"

FAQ

Can I remove multiple patterns at once?

Yes. Supply pattern as a string array or cell array. Each pattern is removed in order from every element of the input text.

What happens if pattern is empty?

An empty pattern list leaves the input unchanged. Empty string patterns are ignored because removing empty text would have no effect.

Does erase modify the original data?

No. It returns a new value with substrings removed. The input variables remain unchanged.

How are missing string scalars handled?

They propagate unchanged. Calling erase on <missing> returns <missing>, matching MATLAB.

Can erase operate on GPU-resident data?

Indirectly. RunMat automatically gathers GPU values to the host, performs the removal, and returns a host result. No explicit gpuArray calls are required.

How do I remove substrings using patterns or regular expressions?

Use replace for literal substitution or regexprep for regular expressions when you need pattern-based removal rather than literal substring erasure.

See Also

replace, strrep, split, regexprep, string

Source & Feedback