Enum ClassWeight 

pub enum ClassWeight<F> {
    None,
    Balanced,
    Explicit(Vec<(usize, F)>),
}

Per-class weighting for DecisionTreeClassifier.

Mirrors sklearn.tree.DecisionTreeClassifier’s class_weight parameter (sklearn/tree/_classes.py:801-820, constraint {dict, list, 'balanced', None}, _classes.py:942). sklearn expands class_weight to PER-SAMPLE weights via compute_sample_weight(class_weight, y) and folds them into the tree’s sample_weight (_classes.py:310-367); every weighted quantity (node class counts, gini/entropy, the leaf value_/predict_proba, and the min_weight_fraction_leaf gate) is then computed on those weights.

Mirrors ferrolearn_linear::svm::ClassWeight for cross-estimator consistency, but is defined locally (no cross-crate import). DecisionTreeRegressor has NO class_weight (sklearn _classes.py:1317), so this lives only on the classifier.

Variants

None

Uniform weights (all classes weighted 1.0). The default (class_weight=None). Produces a byte-identical tree to the unweighted build.

Balanced

Balanced weights n_samples / (n_classes · count_c) per class c, matching sklearn.utils.compute_class_weight("balanced", ...) (class_weight.py:72: n_samples / (n_classes * np.bincount(y))).

Explicit(Vec<(usize, F)>)

Explicit class-label → weight map. Classes absent from the map default to 1.0, matching the dict branch of compute_class_weight (class_weight.py:74-86).

Trait Implementations

impl<F: Clone> Clone for ClassWeight<F>

fn clone(&self) -> ClassWeight<F>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<F: Debug> Debug for ClassWeight<F>

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

Formats the value using the given formatter.

impl<F> Default for ClassWeight<F>

fn default() -> ClassWeight<F>

Returns the “default value” for a type.

impl<'de, F> Deserialize<'de> for ClassWeight<F>

where F: Deserialize<'de>,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<F: PartialEq> PartialEq for ClassWeight<F>

fn eq(&self, other: &ClassWeight<F>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<F> Serialize for ClassWeight<F>

where F: Serialize,

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<F> StructuralPartialEq for ClassWeight<F>