creativity::data::Equation Class Reference

Class to store a equation. More...

#include <creativity/data/Equation.hpp>

Classes
class	Proxy
	Proxy object returned by << that allows more variables to be appended with +. More...

Public Member Functions
	Equation ()=delete
	Not default constructible.
	Equation (Equation &&move)=default
	Move constructor.
	Equation (const Equation &copy)=default
	Copy constructor.
	Equation (const std::shared_ptr< const Variable > &y)
	Creates an equation with the given dependent variable.
Proxy	operator% (const std::shared_ptr< const Variable > &var)
	Adds a variable (lvalue version). More...
Proxy	operator% (double c)
	% d for double d is equivalent to % ConstantVariable(d).
Equation	operator+ (const std::shared_ptr< const Variable > &var) const &
	The addition operator duplicates the called-upon Equation an adds a new term to the duplicate, then returns it.
Equation	operator+ (const std::shared_ptr< const Variable > &var) &&
	The addition operator called on a temporary adds a new term to the temporary, then returns it.
Equation	operator+ (double c) const &
	Adding a double constant (typically 0 or 1) converts the constant to a ConstantVariable.
Equation	operator+ (double c) &&
	Adding a double constant (typically 0 or 1) converts the constant to a ConstantVariable.
std::shared_ptr< const Variable >	depVar () const
	Accesses the dependent variable.
unsigned int	numVars () const
	Returns the number of independent variables.
bool	hasConstant () const
	Returns true if the model includes a constant, false if it does not. More...
std::vector< std::string >	names () const
	Returns the names of the variables in the same order they will be returned by begin()/end().
std::list< std::shared_ptr< const Variable > >::const_iterator	begin () const
	Const access to the beginning iterator of independent variables. More...
std::list< std::shared_ptr< const Variable > >::const_iterator	end () const
	Const access to the past-the-end iterator of independent variables.

Protected Member Functions
void	addVar (const std::shared_ptr< const Variable > &var)
	Internal method to add a variable to the model.

Protected Attributes
std::shared_ptr< const Variable >	dep_var_
	The dependent variable.
std::list< std::shared_ptr< const Variable > >	indep_vars_ {{ConstantVariable::create()}}
	The independent variables; the first is always a ConstantVariable.

Friends
std::ostream &	operator<< (std::ostream &os, const Equation &eq)
	Overloaded so that an Equation can be sent to an output stream, resulting in output such as y ~ const + x1 + x2.

Detailed Description

Class to store a equation.

The class is constructed with the dependent variable, then has an equation added to it using the % operator. For example:

// Constructing a single equation
Equation model(depvar);
model % 1 + var1 + var2;
model % var3;

// Building on another equation:
Equation model2 = model1 + var4;

// rvalue construction
Equation(depvar) + 1 + var1 + var2;

NB: The left-shift operator (<<) would make more logical sense than %, but has the unfortunately pitfall of being of lower precedence than +, which means, in the above example, the 1+var1+var2 term would construct a single, compound variable rather than adding 3 separate variables to the equation.

Member Function Documentation

begin()

std::list<std::shared_ptr<const Variable> >::const_iterator creativity::data::Equation::begin

(

)

const

Const access to the beginning iterator of independent variables.

If an explicit constant of 0 has been added to the model, this will skip the constant; otherwise the constant will be the first element.

hasConstant()

bool creativity::data::Equation::hasConstant

(

)

const

Returns true if the model includes a constant, false if it does not.

If the model has a constant, it is guaranteed to be the first Variable accessed via begin().

operator%()

Proxy creativity::data::Equation::operator%

(

const std::shared_ptr< const Variable > &

var

)

Adds a variable (lvalue version).

If the value is a ConstantVariable with value 0, the constant is removed from the equation; other ConstantVariable values replace (or re-add, if previously removed) the constant. Other types of variables are added to the equation.

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

• creativity/data/Equation.hpp