mbl_select_n_from_m Class Reference

A class which returns an N element subset of the integers [0..M-1]. More...

#include <mbl_select_n_from_m.h>

List of all members.

Public Member Functions
	mbl_select_n_from_m ()
	Dflt ctor.
	mbl_select_n_from_m (unsigned int n, unsigned int m)
	Construct to select n from m.
void	set_n_m (unsigned int new_n, unsigned int new_m)
	Construct to select n from m.
void	use_random (bool flag)
	If true then use random subsets.
void	reseed (long)
	Reseed randomiser.
bool	reset ()
	Reset to first example. Returns true if there is a valid first example.
bool	next ()
	Generate next set. Return true until all combinations exhausted.
bool	is_done () const
	Returns true when all sets enumerated.
const vcl_vector< int > &	subset () const
	Current subset of n from m.
const vcl_vector< int > &	complement ()
	Sub-set not chosen (m-n) from m.
Private Attributes
unsigned int	n_
unsigned int	m_
bool	is_done_
bool	use_random_
vcl_vector< int >	index_
vcl_vector< int >	not_index_
mbl_random_n_from_m	random_

---

Detailed Description

A class which returns an N element subset of the integers [0..M-1].

By default it systematically steps through all combinations of choosing N integers from a set of 0..M-1 Thus when N=1 repeated calls to subset() return 1,2,3,4,...,M When N=2 calls to subset give (0,1), (0,1) .. (0,M-1), (1,2), (1,3),..(M-2,M-1) However, the use_random() function allows random examples to be returned (using the mbl_random_n_from_m class). When N > M, nothing is returned, ie, next() immediately returns false. When N == 0, the empty set is returned. The complement() function returns the integers not in the subset.

The following code snippet runs process_data() on all possible subsets:

  mbl_select_n_from_m selector(3,5);
  if (selector.reset())
  do
  {
    process_data(selector.subset());
  } while selector.next();

Definition at line 30 of file mbl_select_n_from_m.h.

---

Constructor & Destructor Documentation

mbl_select_n_from_m::mbl_select_n_from_m

(

)

Dflt ctor.

Definition at line 10 of file mbl_select_n_from_m.cxx.

mbl_select_n_from_m::mbl_select_n_from_m	(	unsigned int	n,
		unsigned int	m
	)

Construct to select n from m.

Definition at line 16 of file mbl_select_n_from_m.cxx.

---

Member Function Documentation

const vcl_vector< int > & mbl_select_n_from_m::complement

(

)

Sub-set not chosen (m-n) from m.

is_done() should not be true when this function is being called

Definition at line 132 of file mbl_select_n_from_m.cxx.

bool mbl_select_n_from_m::is_done

(

)

const [inline]

Returns true when all sets enumerated.

Never returns true when random subsets being chosen

Definition at line 68 of file mbl_select_n_from_m.h.

bool mbl_select_n_from_m::next

(

)

Generate next set. Return true until all combinations exhausted.

Definition at line 75 of file mbl_select_n_from_m.cxx.

void mbl_select_n_from_m::reseed

(

long

s

)

Reseed randomiser.

Definition at line 24 of file mbl_select_n_from_m.cxx.

bool mbl_select_n_from_m::reset

(

)

Reset to first example. Returns true if there is a valid first example.

Definition at line 56 of file mbl_select_n_from_m.cxx.

void mbl_select_n_from_m::set_n_m	(	unsigned int	new_n,
		unsigned int	new_m
	)

Construct to select n from m.

Definition at line 31 of file mbl_select_n_from_m.cxx.

const vcl_vector< int > & mbl_select_n_from_m::subset

(

)

const

Current subset of n from m.

is_done() should not be true when this function is being called

Definition at line 126 of file mbl_select_n_from_m.cxx.

void mbl_select_n_from_m::use_random

(

bool

flag

)

If true then use random subsets.

Definition at line 46 of file mbl_select_n_from_m.cxx.

---

Member Data Documentation

vcl_vector<int> mbl_select_n_from_m::index_ [private]

Definition at line 38 of file mbl_select_n_from_m.h.

bool mbl_select_n_from_m::is_done_ [private]

Definition at line 35 of file mbl_select_n_from_m.h.

unsigned int mbl_select_n_from_m::m_ [private]

Definition at line 34 of file mbl_select_n_from_m.h.

unsigned int mbl_select_n_from_m::n_ [private]

Definition at line 33 of file mbl_select_n_from_m.h.

vcl_vector<int> mbl_select_n_from_m::not_index_ [private]

Definition at line 39 of file mbl_select_n_from_m.h.

mbl_random_n_from_m mbl_select_n_from_m::random_ [private]

Definition at line 41 of file mbl_select_n_from_m.h.

bool mbl_select_n_from_m::use_random_ [private]

Definition at line 36 of file mbl_select_n_from_m.h.

---

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

• contrib/mul/mbl/mbl_select_n_from_m.h
• contrib/mul/mbl/mbl_select_n_from_m.cxx