splitapply — Split data into groups and apply a function.
Y = splitapply(func,X,G) splits rows of X by the group vector G and invokes func once per nonmissing group.
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 splitapply 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 splitapply works
- Supports one or more data arguments followed by a grouping vector.
- Callbacks are invoked through RunMat's
fevalpath and may return numeric scalar or nonuniform values. - Integer data arguments retain native class and exact values in each group slice passed to the callback. Typed integer group identifiers are a RunMat-only extension and are compared without floating-point conversion.
Example
Sum by group
Y = splitapply(@sum,[1;2;3;4],[2;1;2;1])Expected output:
Y = [6; 4]Using splitapply with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how splitapply changes the result.
Run a small splitapply example, explain the result, then change one input and compare the output.
Related Array functions
Grouping
accumarray · combinations · discretize · findgroups · groupcounts · grp2idx
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 splitapply is executed, line by line, in Rust.
- View the source for splitapply 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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