ppforest2::stats::GroupPartition Class Reference

Contiguous-block representation of grouped observations. More...

#include <GroupPartition.hpp>

Public Member Functions
	GroupPartition (types::ResponseVector const &y)
	Construct from a sorted response vector.
types::FeatureMatrix	bgss (types::FeatureMatrix const &x) const
	Between-group sum of squares matrix (p × p).
GroupPartition	collapse () const
	Collapse all groups into a single supergroup.
auto	data (types::FeatureMatrix const &x) const
	Extract all rows across all groups.
auto	group (types::FeatureMatrix const &x, Group const &group) const
	Extract rows belonging to a group (or supergroup).
int	group_end (Group const &group) const
	Last row index (inclusive) of the block for group.
int	group_size (Group const &group) const
	Number of observations in group.
int	group_start (Group const &group) const
	First row index of the block for group.
types::FeatureVector	mean (types::FeatureMatrix const &x) const
	Overall mean of all grouped rows (p).
GroupPartition	remap (GroupMap const &mapping) const
	Merge groups according to a mapping.
GroupPartition	subset (GroupSet groups) const
	Create a partition containing only the given groups.
types::FeatureMatrix	wgss (types::FeatureMatrix const &x) const
	Within-group sum of squares matrix (p × p).

Static Public Member Functions
static bool	is_contiguous (GroupVector const &y)
	Check whether all equal values in y form a single contiguous block.

Public Attributes
GroupSet const	groups
	Set of all group labels in this partition.
GroupInvMap const	subgroups
	Maps each group to its set of subgroups.
GroupMap const	supergroups
	Maps each group to its supergroup (identity if no merge).

Detailed Description

Contiguous-block representation of grouped observations.

Assumes the response vector is sorted so that observations of the same group are contiguous. Stores the start/end row indices of each group block and provides efficient extraction, subsetting, and computation of between- and within-group statistics.

Groups can be hierarchically merged via remap(), which assigns supergroup labels while tracking the original subgroups.

// y must be sorted so equal values are contiguous.
GroupPartition gp(y);
 
// Extract rows belonging to group 0:
auto x_group0 = gp.group(x, 0);
 
// Between- and within-group statistics:
auto B = gp.bgss(x);   // between-group sum of squares (p × p)
auto W = gp.wgss(x);   // within-group sum of squares  (p × p)
 
// Restrict to a subset of groups:
GroupPartition sub = gp.subset({0, 2});

Constructor & Destructor Documentation

GroupPartition()

ppforest2::stats::GroupPartition::GroupPartition

(

types::ResponseVector const &

y

)

Construct from a sorted response vector.

Parameters

y	Response vector (n) with contiguous group blocks.

Member Function Documentation

bgss()

types::FeatureMatrix ppforest2::stats::GroupPartition::bgss

(

types::FeatureMatrix const &

x

)

const

Between-group sum of squares matrix (p × p).

collapse()

GroupPartition ppforest2::stats::GroupPartition::collapse

(

)

const

Collapse all groups into a single supergroup.

Returns

New GroupPartition with one supergroup containing all groups.

data()

auto ppforest2::stats::GroupPartition::data ( types::FeatureMatrix const & x ) const

inline

Extract all rows across all groups.

Parameters

x	Feature matrix (n × p).

Returns

Sub-matrix with all grouped rows.

group()

auto ppforest2::stats::GroupPartition::group ( types::FeatureMatrix const & x, Group const & group ) const

inline

Extract rows belonging to a group (or supergroup).

Parameters

x	Feature matrix (n × p).
group	Group label.

Returns

Sub-matrix of rows belonging to group.

group_end()

int ppforest2::stats::GroupPartition::group_end

(

Group const &

group

)

const

Last row index (inclusive) of the block for group.

group_size()

int ppforest2::stats::GroupPartition::group_size

(

Group const &

group

)

const

Number of observations in group.

group_start()

int ppforest2::stats::GroupPartition::group_start

(

Group const &

group

)

const

First row index of the block for group.

is_contiguous()

static bool ppforest2::stats::GroupPartition::is_contiguous ( GroupVector const & y )

static

Check whether all equal values in y form a single contiguous block.

mean()

types::FeatureVector ppforest2::stats::GroupPartition::mean

(

types::FeatureMatrix const &

x

)

const

Overall mean of all grouped rows (p).

remap()

GroupPartition ppforest2::stats::GroupPartition::remap

(

GroupMap const &

mapping

)

const

Merge groups according to a mapping.

Parameters

mapping

Maps original group labels to supergroup labels.

Returns

New GroupPartition with merged groups.

subset()

GroupPartition ppforest2::stats::GroupPartition::subset

(

GroupSet

groups

)

const

Create a partition containing only the given groups.

Parameters

groups

Set of group labels to keep.

Returns

New GroupPartition restricted to groups.

wgss()

types::FeatureMatrix ppforest2::stats::GroupPartition::wgss

(

types::FeatureMatrix const &

x

)

const

Within-group sum of squares matrix (p × p).

Member Data Documentation

groups

GroupSet const ppforest2::stats::GroupPartition::groups

Set of all group labels in this partition.

subgroups

GroupInvMap const ppforest2::stats::GroupPartition::subgroups

Maps each group to its set of subgroups.

supergroups

GroupMap const ppforest2::stats::GroupPartition::supergroups

Maps each group to its supergroup (identity if no merge).

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The documentation for this class was generated from the following file:

• core/src/stats/GroupPartition.hpp