bio_expression.Elem Class Reference

Class extracting an expression from a dictionary. More...

Inheritance diagram for bio_expression.Elem:

Public Member Functions
def	__init__ (self, dictionary, key, default=Numeric(0))
def	getExpression (self)
def	getID (self)
Public Member Functions inherited from bio_expression.Expression
def	__init__ (self)
	Constructor.
def	getExpression (self)
def	getID (self)
def	__str__ (self)
def	__neg__ (self)
def	__add__ (self, expression)
def	__radd__ (self, expression)
def	__sub__ (self, expression)
def	__rsub__ (self, expression)
def	__mul__ (self, expression)
def	__rmul__ (self, expression)
def	__div__ (self, expression)
def	__rdiv__ (self, expression)
def	__truediv__ (self, expression)
	Support for Python version 3.x. More...
def	__rtruediv__ (self, expression)
	Support for Python version 3.x. More...
def	__mod__ (self, expression)
def	__pow__ (self, expression)
def	__rpow__ (self, expression)
def	__and__ (self, expression)
def	__or__ (self, expression)
def	__eq__ (self, expression)
def	__ne__ (self, expression)
def	__le__ (self, expression)
def	__ge__ (self, expression)
def	__lt__ (self, expression)
def	__gt__ (self, expression)

Public Attributes
	prob
	choice
	default
	operatorIndex
Public Attributes inherited from bio_expression.Expression
	operatorIndex

Detailed Description

Class extracting an expression from a dictionary.

A typical example consists in returning the probability of a chosen alternative in a choice model. Consider the following dictionary:

P = {  1: exp(V1) / (exp(V1)+exp(V2)+exp(V3)),
2: exp(V2) / (exp(V1)+exp(V2)+exp(V3)),
3: exp(V3) / (exp(V1)+exp(V2)+exp(V3))}

and assume that the variable Choice in the data file contains the identifier of the chosen alternative of the corresponding observation, that is 1, 2 or 3. Then, the probability of the chosen alternative is given by

chosenProba = Elem(P,Choice)

If the result of "Choice" does not correspond to any valid entry in the dictionary, a warning is issued and the value of the default expression is returned. The warning is issued because this situation is usually not wanted by the user. To turn off the warning, set the parameter warnsForIllegalElements to 0.

Definition at line 871 of file bio_expression.py.

Constructor & Destructor Documentation

def bio_expression.Elem.__init__	(		self,
			dictionary,
			key,
			default = Numeric(0)
	)

Parameters

dictionary	A dictionary (see Python documentation) such that the indices are numerical values that can match the result of an expression
key	expression identifying the entry in the dictionary If the result of key does not correspond to any valid entry in the dictionary, the value of the default expression is returned. This argument is optional. If omitted, the default value is 0.

Definition at line 880 of file bio_expression.py.

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

• bio_expression.py