variable

Class

class Variable(name: str, values: list = [], B_flag: str = 'auto')

A class to manage information about a variable.

Parameters:

name (str) – Name of the variable. This is just for identification purposes and does not affect analysis results.
values (list) – Description of basic states. The corresponding location of each state in the list is used as the state index. When applicable, use an ordering where lower indices represent worse outcomes, as some modules assume this ordering. For example: ['failure', 'survival'] since 0 < 1.
B_flag (str) –
Flag to determine how B is generated. Options are:
- ’store’: the mapping matrix is generated and stored.
- ’fly’: the mapping matrix is generated on the fly during inference.
- ’auto’: the mapping matrix is generated and stored if the number of basic states is less than or equal to 6; otherwise, it is generated on the fly.
Since the number of states increases exponentially with the number of basic states, it is recommended to use ‘auto’ or ‘fly’ for large numbers of basic states.

Example Usage

from mbnpy.variable import Variable

# Define basic states
basic_states = ['failure', 'survival']

# Create a Variable instance
var = Variable(name='Outcome', values=basic_states)

# Generate the mapping matrix
mapping_matrix = var.gen_B()
print(f"Mapping Matrix: {mapping_matrix}")

# Get state index from a set of basic states
state_index = var.get_state({1})
print(f"State Index for {{1}}: {state_index}")

# Get set of basic states from a state index
state_set = var.get_set(0)
print(f"State Set for index 0: {state_set}")

# Get state index from a binary vector
state_index_from_vector = var.get_state_from_vector([0, 1])
print(f"State Index from vector [0, 1]: {state_index}")

Output:

Mapping Matrix: [{0}, {1}, {0, 1}]
State Index for {1}: 1
State Set for index 0: {0}
State Index from vector [0, 1]: 1

Methods

gen_B

Variable.gen_B()

Generates the mapping matrix.

Returns:: Mapping matrix.
Return type:: list of sets

update_B

Variable.update_B()

Updates the mapping matrix based on current values and B_flag. To be used when the values or B_flag are updated.

Example:

basic_states = ['failure', 'survival', 'improved']
var.values = basic_states
var.update_B()
print(var)

Output:

Variable(name='Survival',
         values=['failure', 'survival', 'improved'],
         B=[{0}, {1}, {2}, {0, 1}, {0, 2}, {1, 2}, {0, 1, 2}])

get_state

Variable.get_state(state_set: set)

Finds the state index of a given set of basic states.

Parameters:: state_set (set) – Set of basic states.
Returns:: State index in B matrix of the given set.
Return type:: int

Example:

state_index = var.get_state({0, 1})
print(state_index)

Output:

get_set

Variable.get_set(state: int)

Finds the set of basic states represented by a given state index.

Parameters:: state (int) – State index.
Returns:: Set of basic states.
Return type:: set

Example:

state_set = var.get_set(3)
print(state_set)

Output:

{0, 1}

get_state_from_vector

Variable.get_state_from_vector(vector: list)

Finds the state index for a given binary vector.

Parameters:: vector (list) – Binary vector. 1 if the basic state is involved, 0 otherwise.
Returns:: State index.
Return type:: int
Raises:: ValueError – If the vector is not the same length as the number of basic states.

Example:

state_index_from_vector = var.get_state_from_vector([1, 1, 0])
print(state_index_from_vector)

Output: