RunMat
GitHub

View all functions

CategoryStrings: Search

What does the contains function do in MATLAB / RunMat?

contains(str, pattern) returns a logical result indicating whether each element of str contains the corresponding text in pattern. The builtin supports string arrays, character vectors/arrays, and cell arrays of character vectors, honouring MATLAB's implicit expansion semantics.

How does the contains function behave in MATLAB / RunMat?

  • Accepts text inputs as string scalars/arrays, character scalars/arrays, or cell arrays of character vectors.
  • Accepts patterns in the same formats. Either input may be scalar; when sizes differ MATLAB-style implicit expansion applies.
  • Missing string scalars (<missing>) never match any pattern.
  • Empty pattern values ("" or '') always match non-missing text elements.
  • The optional 'IgnoreCase', true|false name-value pair controls case sensitivity (default is case-sensitive).
  • Returns a logical scalar when the broadcasted size is one element, otherwise returns a logical array with the broadcasted shape.

contains Function GPU Execution Behaviour

contains performs host-side text comparisons. When invoked with data that currently resides on the GPU, RunMat gathers the inputs before executing the search so that results match MATLAB exactly. No provider hooks are required for this builtin.

Examples of using the contains function in MATLAB / RunMat

Check if a string contains a substring

tf = contains("RunMat Accelerate", "Accelerate");

Expected output:

tf = logical
   1

Perform a case-insensitive search

tf = contains("RunMat", "run", 'IgnoreCase', true);

Expected output:

tf = logical
   1

Apply a scalar pattern to every element of a string array

labels = ["alpha" "beta" "gamma"];
tf = contains(labels, "a");

Expected output:

tf = 1×3 logical array
   1   1   1

Match element-wise patterns with implicit expansion

names = ["hydrogen"; "helium"; "lithium"];
patterns = ["gen"; "ium"; "iron"];
tf = contains(names, patterns);

Expected output:

tf = 3×1 logical array
   1
   1
   0

Search a cell array of character vectors

C = {'Mercury', 'Venus', 'Mars'};
tf = contains(C, 'us');

Expected output:

tf = 1×3 logical array
   0   1   0

Provide multiple patterns as a column vector

tf = contains("saturn", ['s'; 'n'; 'x']);

Expected output:

tf = 3×1 logical array
   1
   1
   0

Handle empty and missing text values

texts = ["", "<missing>"];
tf = contains(texts, "");

Expected output:

tf = 1×2 logical array
   1   0

GPU residency in RunMat (Do I need gpuArray?)

You usually do NOT need to call gpuArray yourself in RunMat (unlike MATLAB).

contains always executes on the host, but RunMat's runtime automatically gathers any GPU-resident inputs before evaluating the text search so behaviour is identical to MATLAB. You can still call gpuArray manually for compatibility with legacy MATLAB code; the runtime will gather those inputs just in time when contains runs.

FAQ

What types can I pass to contains?

Use string scalars/arrays, character vectors/arrays, or cell arrays of character vectors for both the text and the pattern. Mixed combinations are accepted, and RunMat performs MATLAB-style implicit expansion when the array sizes differ.

How do I ignore letter case?

Specify 'IgnoreCase', true (or 'on') after the pattern argument. The option is case-insensitive, so 'ignorecase' also works. The default is false, matching MATLAB.

What happens with empty patterns?

Empty patterns ("" or '') always match non-missing text elements. When the text element is missing (<missing>), the result is false.

Can I search for multiple patterns at once?

Yes. Provide pattern as a string array, character array, or cell array of character vectors. RunMat applies implicit expansion so that scalar inputs expand across the other argument automatically.

How are missing strings treated?

Missing string scalars (displayed as <missing>) never match any pattern and produce false in the result. Use ismissing if you need to separate missing values before calling contains.

Does contains run on the GPU?

No. The builtin executes on the CPU. If inputs reside on the GPU (for example, after other accelerated operations), RunMat gathers them automatically so behaviour matches MATLAB.

Does contains preserve the input shape?

Yes. The output is a logical array whose shape is the implicit-expansion result of the input shapes. When the broadcasted shape has exactly one element, the builtin returns a logical scalar.

See Also

startsWith, endsWith, regexp, regexpi

Source & Feedback