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. A TidyView that has been grouped by one or more columns.

Created by TidyView::group_by. Holds the original view plus a GroupIndex that maps rows to groups. Call summarise to aggregate or ungroup to return to a flat view.

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.