andes.core.discrete.Selector

class andes.core.discrete.Selector(*args, fun, tex_name=None, info=None)

Selection between two variables using the provided reduce function.

The reduce function should take the given number of arguments. An example function is np.maximum.reduce which can be used to select the maximum.

Names are in s0, s1.

Warning

A potential bug when more than two inputs are provided, and values in different inputs are equal. Only two inputs are allowed.

Deprecated since version 1.5.9: Use of this class for comparison-based output is discouraged. Instead, use LessThan and Limiter to construct piesewise equations.

See the new implementation of HVGate and LVGate.

See also

numpy.ufunc.reduce

NumPy reduce function

Notes

A common pitfall is the 0-based indexing in the Selector flags. Note that exported flags start from 0. Namely, s0 corresponds to the first variable provided for the Selector constructor.

Examples

Example 1: select the largest value between v0 and v1 and put it into vmax.

After the definitions of v0 and v1, define the algebraic variable vmax for the largest value, and a selector vs

self.vmax = Algeb(v_str='maximum(v0, v1)',
                  tex_name='v_{max}',
                  e_str='vs_s0 * v0 + vs_s1 * v1 - vmax')

self.vs = Selector(self.v0, self.v1, fun=np.maximum.reduce)

The initial value of vmax is calculated by maximum(v0, v1), which is the element-wise maximum in SymPy and will be generated into np.maximum(v0, v1). The equation of vmax is to select the values based on vs_s0 and vs_s1.

__init__(*args, fun, tex_name=None, info=None)

Methods

check_eq(**kwargs)	This function is called in l_check_eq after updating equations.
check_iter_err([niter, err])	Check if the minimum iteration or maximum error is reached so that this discrete block should be enabled.
check_var(*args, **kwargs)	Set the i-th variable's flags to 1 if the return of the reduce function equals the i-th input.
get_limit_report()	Return a list of dicts describing variables clamped at limits.
get_names()	Available symbols from this class
get_tex_names()	Return tex_names of exported flags.
get_values()
list2array(n)	Allocate memory for the discrete flags specified in self.export_flags.
save_unconstrained()	Save the input variable's unconstrained value (call after init pass 1).

Attributes

class_name