docplex.mp.pwl module¶

class
docplex.mp.pwl.
PwlFunction
(model, pwl_def, name=None)[source]¶ Bases:
docplex.mp.basic.ModelingObjectBase
This class models piecewise linear (PWL) functions. This class is not intended to be instantiated: piecewise linear functions are defined by invoking
docplex.mp.model.Model.piecewise()
, ordocplex.mp.model.Model.piecewise_as_slopes()
.Piecewiselinear functions are important in many applications. They are often specified either:
 by giving a set of slopes, a set of breakpoints at which the slopes change, and the value of the functions at a given point, or
 by giving an ordered list of (x,y) points that are linearly connected, along with the slope before the first point and the slope after the last point.
Note that a piecewiselinear function may be discontinuous.

add
(arg)[source]¶ Adds an expression to self.
Note
This method does not create a new PWL function but modifies the self instance.
Parameters: arg – The expression to be added. Can be a PWL function or a number. Returns: The modified self.

clone
()[source]¶ Creates a copy of the PWL function on the same model.
Returns: The copy of the PWL function.

divide
(arg)[source]¶ Divides this PWL function by a number.
Note
This method does not create a new function but modifies the self instance.
Parameters: arg – The number that is used to divide self. Returns: The modified self.

evaluate
(x_val)[source]¶ Evaluates the PWL function at the point whose xcoordinate is x_val.
Parameters: x_val – The x value for which we want to compute the value of the function. Returns: The value of the PWL function at point x_val. A DOcplexException exception is raised when evaluating at a discontinuity of the PWL function.

multiply
(arg)[source]¶ Multiplies this PWL function by a number.
Note
This method does not create a new function but modifies the self instance.
Parameters: arg – The number that is used to multiply self. Returns: The modified self.

plot
(lx=None, rx=None, k=1, **kwargs)[source]¶ This method displays the piecewise linear function using the matplotlib package, if found.
Parameters:  lx – The value to show the preslope (must be before the first breakpoint x value).
 rx – The value to show the postslope (must be after the last breakpoint x value).
 k – Scaling factor to calculate default values for rx and/or lx if these arguments are not provided, based on mean interval length between the x values of breakpoints.
 kwargs – additional arguments to be passed to matplotlib plot() function

subtract
(arg)[source]¶ Subtracts an expression from this PWL function.
Note
This method does not create a new function but modifies the self instance.
Parameters: arg – The expression to be subtracted. Can be either a PWL function, or a number. Returns: The modified self.

translate
(arg)[source]¶ Translate this PWL function by a number. This method creates a new PWL function instance for which all breakpoints have been moved along the horizontal axis by the amount specified by arg.
Parameters: arg – The number that is used to translate all breakpoints. Returns: The translated PWL function.