Struct GroupedTidyView 

pub struct GroupedTidyView { /* private fields */ }

A grouped view produced by TidyView::group_by(...).

Holds the original TidyView (unchanged) plus a GroupIndex over its visible rows. No column data is copied.

After grouping, ungroup() restores the plain TidyView. summarise() collapses each group into one summary row.

Implementations

impl GroupedTidyView

pub fn ngroups(&self) -> usize

Return the number of groups.

pub fn ungroup(self) -> TidyView

Discard grouping, returning the original TidyView unchanged.

pub fn group_index(&self) -> &GroupIndex

Access the group index (for testing/inspection).

pub fn summarise( &self, assignments: &[(&str, TidyAgg)], ) -> Result<TidyFrame, TidyError>

Collapse each group to one summary row using named aggregators.

assignments is an ordered list of (output_name, aggregator). Output rows are in first-occurrence group order (deterministic).

The result is a TidyFrame containing: • One column per group key (in key order) • One column per aggregator (in assignment order)

Aggregator semantics (empty group): • count → 0 • sum → 0.0 • mean → f64::NAN • min → f64::NAN • max → f64::NAN • first / last → TidyError::EmptyGroup

impl GroupedTidyView

pub fn mutate_across( &self, specs: &[AcrossSpec], ) -> Result<TidyFrame, TidyError>

Apply across transformations then mutate each group in-place.

For each group, applies each AcrossSpec transform to the specified columns, producing output named {col}_{fn} (or per-template). Returns a materialized TidyFrame with all groups combined.

pub fn summarise_across( &self, specs: &[AcrossSpec], ) -> Result<TidyFrame, TidyError>

Summarise with across transforms: apply each transform to each column, collecting one aggregate value per group.

The specs use AcrossSpec where the transform function must return a single-element column (scalar reduction). If it returns more than one row, TidyError::LengthMismatch is returned.

Trait Implementations

impl Clone for GroupedTidyView

fn clone(&self) -> GroupedTidyView

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GroupedTidyView

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

Formats the value using the given formatter.