Struct Frame 

pub struct Frame(/* private fields */);

Rows and columns, together with what each column is called and holds.

A type of ours rather than a RecordBatch in an Opaque for two reasons that are not style: a codec is an impl of somebody else’s trait and the orphan rule wants one of the two types to be ours, and this is the word the design is written in — the difference between training and deploying is how many rows the frame brings.

It is not a tensor and does not want to be. Numbers and fixed-size lists of them are contiguous Arrow buffers, so converting is a reshape and not a copy; text is not a tensor until something tokenizes it. The conversion is a node, and the same node whether the frame came from a file or a topic.

Implementations

impl Frame

pub const KIND: &'static str = "arrow.RecordBatch"

What gets written beside the bytes. Named after the format and not the language: what is on disk is an Arrow IPC stream, and whoever reads it back may be a polars on the other side of the wall.

pub fn new(batch: RecordBatch) -> Self

This batch, as a frame.

pub fn rows(&self) -> usize

How many rows it brings. The only number a caller usually wants: it is what says whether a span was short because the dataset ended.

pub fn schema(&self) -> &SchemaRef

What the columns are called and what they hold — without reading a value, which is the half of a virtual table worth having.

pub fn batch(&self) -> &RecordBatch

The batch itself, for whoever brought their own engine.

pub fn value(self) -> Value

As a value, which is how it crosses an edge. Opaque and not a variant of its own: the core has no dependencies and is not going to learn what a column is.

pub fn of(value: &Value) -> Option<&Self>

The frame this value carries, if it carries one.

pub fn written(&self) -> Result<Vec<u8>, FrameError>

What it weighs in bytes: Arrow IPC, buffers and all. No encoding pass and no per-value work, which is the reason Arrow is the type that crosses an edge rather than something converted to at the edges.

pub fn read(bytes: &[u8]) -> Result<Self, FrameError>

And back.

One frame, however many batches the stream holds: what was written down was a frame, and a frame is what comes back.

Trait Implementations

impl Clone for Frame

fn clone(&self) -> Frame

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Frame

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.