Struct Sample 

pub struct Sample { /* private fields */ }

One training example: an insertion-ordered map from file extension to value.

Fields whose names start with __ are metadata and are skipped by decoding, encoding, and key extraction.

use webdataset_core::{Sample, Value};

let mut sample = Sample::with_key("image0001");
sample.insert("cls", Value::Int(7));
sample.insert("txt", Value::Text("a caption".into()));

assert_eq!(sample.key(), Some("image0001"));
assert_eq!(sample.get("cls").and_then(Value::as_i64), Some(7));
assert_eq!(sample.field_names(), vec!["cls", "txt"]);

Implementations

impl Sample

pub fn new() -> Sample

An empty sample with no fields at all.

pub fn with_key(key: impl Into<String>) -> Sample

An empty sample carrying only its __key__.

pub fn key(&self) -> Option<&str>

The sample’s __key__, if it has one.

pub fn url(&self) -> Option<&str>

The URL of the shard this sample came from.

pub fn local_path(&self) -> Option<&str>

The on-disk path of the shard, when it was read or cached locally.

pub fn set_key(&mut self, key: impl Into<String>)

Set the __key__ field.

pub fn set_url(&mut self, url: impl Into<String>)

Set the __url__ field.

pub fn get(&self, name: &str) -> Option<&Value>

Look up a field.

pub fn get_mut(&mut self, name: &str) -> Option<&mut Value>

Look up a field for modification.

pub fn get_first(&self, names: &[&str]) -> Option<&Value>

Look up the first field that exists among several alternatives.

Alternatives are given either as a slice or, following the Python API, as a single ;-separated string (see Sample::get_first_spec).

pub fn get_first_spec(&self, spec: &str) -> Option<&Value>

Look up the first field named by a ;-separated alternation such as "png;jpg;jpeg".

pub fn require_first_spec(&self, spec: &str) -> Result<&Value>

Like Sample::get_first_spec but reports which alternatives were tried.

pub fn insert( &mut self, name: impl Into<String>, value: impl Into<Value>, ) -> Option<Value>

Insert a field, returning the value it replaced.

pub fn remove(&mut self, name: &str) -> Option<Value>

Remove a field, returning its value.

pub fn contains_key(&self, name: &str) -> bool

Whether a field is present.

pub fn len(&self) -> usize

The number of fields, metadata included.

pub fn is_empty(&self) -> bool

Whether the sample has no fields at all.

pub fn iter(&self) -> MapIter<'_, String, Value>

Iterate over all fields in insertion order.

pub fn keys(&self) -> impl Iterator<Item = &str>

All field names, metadata included.

pub fn field_names(&self) -> Vec<&str>

The names of the data (non-__) fields.

pub fn as_map(&self) -> &Fields

Borrow the underlying map.

pub fn into_map(self) -> Fields

Consume the sample and return the underlying map.

pub fn is_valid(&self) -> bool

Whether this sample should be passed downstream.

Mirrors valid_sample in the Python implementation: a sample is valid when it has at least one field and is not marked __bad__.

pub fn rename(&mut self, from: &str, to: impl Into<String>) -> bool

Rename a field, preserving its position in the field order.

Trait Implementations

impl Clone for Sample

fn clone(&self) -> Sample

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Sample

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

Formats the value using the given formatter.

impl Default for Sample

fn default() -> Sample

Returns the “default value” for a type.

impl From<IndexMap<String, Value, BuildHasherDefault<Fnv1a>>> for Sample

fn from(fields: Fields) -> Sample

Converts to this type from the input type.

impl FromIterator<(String, Value)> for Sample

fn from_iter<T: IntoIterator<Item = (String, Value)>>(iter: T) -> Sample

Creates a value from an iterator.

impl Index<&str> for Sample

type Output = Value

The returned type after indexing.

fn index(&self, name: &str) -> &Value

Performs the indexing (container[index]) operation.

impl<'a> IntoIterator for &'a Sample

type Item = (&'a String, &'a Value)

The type of the elements being iterated over.

type IntoIter = Iter<'a, String, Value>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl IntoIterator for Sample

type Item = (String, Value)

The type of the elements being iterated over.

type IntoIter = IntoIter<String, Value>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl PartialEq for Sample

fn eq(&self, other: &Sample) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Sample