head — Return the first rows of a table, timetable, or array.
head(A, n) selects the first n rows. The default row count is 8. All eight integer array classes preserve exact storage and trailing dimensions.
Syntax
B = head(A)
B = head(A, n)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
A | Any | Yes | — | Table, timetable, or array input. |
n | IntegerScalar | Yes | — | Positive number of leading rows to select. |
Returns
| Name | Type | Description |
|---|---|---|
out | Any | Result value. |
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:table:InvalidArgument | Arguments or table metadata are invalid. | table: invalid argument |
RunMat:table:InvalidIndex | Table indexing is invalid. | table: invalid index |
RunMat:table:InvalidVariable | A table variable name or value is invalid. | table: invalid variable |
RunMat:readtable:IOError | readtable cannot open or read the requested file. | readtable: file read failed |
RunMat:readtable:UnsupportedFileType | readtable receives a file type outside the text or spreadsheet import backends. | readtable: unsupported file type |
How head works
- Table/timetable variable metadata is preserved.
- Real, complex, logical, and integer arrays preserve every trailing dimension while selecting along dimension one.
- Typed integer row counts are decoded exactly and must be positive.
- GPU-resident data is supported in MATLAB-compatible modes; a GPU-resident row-count control remains gated before provider access.
Example
First row
H = head(T, 1)Expected output:
H = first row of TUsing head with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how head changes the result.
Run a small head example, explain the result, then change one input and compare the output.
Related Table functions
array2table · array2timetable · categorical · cell2table · dictionary · groupsummary · height · iscategorical · isordinal · istable · istimetable · ordinal · pivot · rowfilter · struct2table · table · table2array · table2cell · table2struct · table2timetable · timerange · timetable · timetable2table · uitable · vartype · width
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how head is executed, line by line, in Rust.
- View the source for head 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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