groupcounts — Count the number of elements in each group.
B = groupcounts(A) returns counts for each sorted group in array data, including the missing group by default. For table input, groupcounts(T,vars) returns a table with grouping variables, GroupCount, and Percent.
Syntax
varargout = groupingBuiltin(args...)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
args | Any | Variadic | — | MATLAB-compatible arguments. |
Returns
| Name | Type | Description |
|---|---|---|
varargout | Any | Builtin outputs. |
Returned values from groupcounts depend on how many outputs the caller requests.
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:grouping:InvalidInput | Inputs are malformed, have incompatible lengths, or request unsupported grouped output. | grouping builtin: invalid input |
RunMat:grouping:CallbackFailed | A grouped callback fails or returns incompatible outputs. | grouping builtin: callback failed |
RunMat:grouping:TooLarge | The requested dense or combinatorial output exceeds RunMat's materialization limit. | grouping builtin: output is too large |
How groupcounts works
- Supports array, cell-array-of-grouping-vectors, and table grouping inputs.
- All eight integer classes are documented grouping data and are compared from authoritative storage, including distinct uint64 values above flintmax.
- The one-group form supports numeric edges and positive bin counts together with IncludedEdge, IncludeEmptyGroups, and IncludeMissingGroups. Exact integer edges never cross a floating comparison boundary. Multi-group bin specifications and time bins are not currently supported.
- Native typed-integer bin counts and boolean controls are independently gated RunMat extensions; equivalent double and logical controls remain available in MATLAB-compatible mode.
- Missing groups are included by default. Count and percentage outputs are double, while unbinned grouping outputs preserve their integer class.
Example
Count groups
B = groupcounts([1;1;2])Expected output:
B = [2; 1]Using groupcounts with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how groupcounts changes the result.
Run a small groupcounts example, explain the result, then change one input and compare the output.
Related Array functions
Grouping
accumarray · combinations · discretize · findgroups · grp2idx · splitapply
Sorting Sets
argsort · intersect · ismember · ismembertol · issorted · issortedrows · setdiff · setxor · sort · sortrows · union · unique
Shape
blkdiag · cat · circshift · diag · flip · fliplr · flipud · horzcat · ipermute · kron · permute · repelem · repmat · reshape · rot90 · squeeze · toeplitz · tril · triu · vertcat
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how groupcounts is executed, line by line, in Rust.
- View the source for groupcounts 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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