Documentation

Train a model. cfg is the hyperparameter config; input is the supervised target Expr a or the unsupervised feature list [Expr Double]; the frame is any ToDataFrame source (an untyped DataFrame or a TypedDataFrame). The config and input together determine the model, so no annotation is needed (a classifier's label type comes from its Expr a target).

A model overrides FrameReq to demand a schema shape (e.g. AllDoubleFrame), which fit enforces at compile time on a typed frame; the default is AnyFrame.

The frame is determined by the input (via FrameFor): an untyped target pairs with a DataFrame and yields the bare model; a typed target (TExpr over cols) pairs with a TypedDataFrame cols and yields a Fitted cols model, so predict gives a typed TExpr. A non-Double typed column is then a compile error.

A model trained on a typed frame, carrying the schema cols as a phantom so its predict yields a typed TExpr. Use fittedModel to recover the bare model record (coefficients, etc.).

The type fit returns for a given frame source: the bare model for an untyped DataFrame, or a schema-tagged Fitted for a TypedDataFrame. Training on an untyped frame is therefore unchanged.

The frame a given training input is fit against: an untyped target/feature input pairs with a plain DataFrame; a typed input (TExpr / [TExpr]) pairs with a TypedDataFrame over the same schema. So the target expression and the frame are forced to share their columns at compile time.

The schema requirement a model places on its training frame. AnyFrame imposes nothing (the default); AllDoubleFrame demands every column be Double.

Turn a model's FrameKind requirement into a constraint on the actual frame type. Untyped DataFrames are never constrained (they are runtime-checked); a typed frame must satisfy the requirement at compile time.

Compile a fitted model's canonical prediction to an expression over the raw columns. The Prediction type tracks the model: a bare model gives Expr r; a Fitted model (trained on a typed frame) gives TExpr cols r.

The typed counterpart of an untyped expression type for schema cols: AsTExpr cols (Expr r) = TExpr cols r. Lets a result type follow the frame — an Expr over a plain frame becomes a TExpr over a typed one.

Lift an untyped expression into its TExpr for schema cols.