Skip to main content

A Python package for binary/multi state systems

Project description

relibmss

A Python package for binary/multi state systems with BDD/MDD.

Installation

pip install relibmss

Usage

Calculate the probability of a fault tree

import relibmss as ms

# Create a fault tree (binary system)
ft = ms.FTree()

# Define events (This version only supports repeated events)
A = ft.defvar('A')
B = ft.defvar('B')
C = ft.defvar('C')

# Make a tree
top = A & B | C # & is AND gate, | is OR gate

# Set probabilities
prob = {
    'A': 0.1,
    'B': 0.2,
    'C': 0.3
}

# Calculate the probability
print(ft.prob(top, prob))

# Set the interval of the probability
prob = {
    'A': (0.1, 0.2),
    'B': (0.2, 0.3),
    'C': (0.3, 0.4)
}

# Calculate the probability
print(ft.prob_interval(top, prob))

Obtain the minimal cut sets

import relibmss as ms

# Create a fault tree (binary system)
ft = ms.FTree()

# Define events (This version only supports repeated events)
A = ft.defvar('A')
B = ft.defvar('B')
C = ft.defvar('C')

# Make a tree
top = ft.kofn(2, [A, B, C]) # k-of-n gate

# Obtain the minimal cut sets
s = ft.mcs(top) # s is a set of minimal cut sets (ZDD representation)

# Convert the ZDD representation to a list of sets
print(s.extract())

Draw a BDD

import relibmss as ms

# Create a binary decision diagram
ft = ms.FTree()

# Define variables
A = ft.defvar('A')
B = ft.defvar('B')
C = ft.defvar('C')

# Make a tree
top = A & B | C

# Draw the BDD
bdd = ft.getbdd(top)
source = bdd.dot() # source is a string of the dot language

# Example: Display the BDD in Jupyter Notebook
from graphviz import Source
from IPython.display import Image, display
Image(Source(source).pipe(format='png'))

An example of a large fault tree

## This is an example of a large fault tree
## Computational time may be long (about 1 minute)

import relibmss as ms

ft = ms.FTree()
c = [ft.defvar("c" + str(i)) for i in range(61)]

g62 = c[0] & c[1]
g63 = c[0] & c[2]
g64 = c[0] & c[3]
g65 = c[0] & c[4]
g66 = c[0] & c[5]
g67 = c[0] & c[6]
g68 = c[0] & c[7]
g69 = c[0] & c[8]
g70 = g62 | c[9]
g71 = g63 | c[10]
g72 = g64 | c[11]
g73 = g65 | c[12]
g74 = g62 | c[13]
g75 = g63 | c[14]
g76 = g64 | c[15]
g77 = g65 | c[16]
g78 = g62 | c[17]
g79 = g63 | c[18]
g80 = g64 | c[19]
g81 = g65 | c[20]
g82 = g62 | c[21]
g83 = g63 | c[22]
g84 = g64 | c[23]
g85 = g65 | c[24]
g86 = g62 | c[25]
g87 = g63 | c[26]
g88 = g64 | c[27]
g89 = g65 | c[28]
g90 = g66 | c[29]
g91 = g68 | c[30]
g92 = g67 | c[31]
g93 = g69 | c[32]
g94 = g66 | c[33]
g95 = g68 | c[34]
g96 = g67 | c[35]
g97 = g69 | c[36]
g98 = g66 | c[37]
g99 = g68 | c[38]
g100 = g67 | c[39]
g101 = g69 | c[40]
g102 = g66 | c[41]
g103 = g68 | c[42]
g104 = g67 | c[43]
g105 = g69 | c[44]
g106 = ft.kofn(3, [g70, g71, g72, g73])
g107 = ft.kofn(3, [g74, g75, g76, g77])
g108 = ft.kofn(3, [g78, g79, g80, g81])
g109 = ft.kofn(3, [g82, g83, g84, g85])
g110 = ft.kofn(3, [g86, g87, g88, g89])
g111 = ft.kofn(3, [g94, g95, g96, g97])
g112 = ft.kofn(3, [g98, g99, g100, g101])
g113 = g90 & g92
g114 = g91 & g93
g115 = g102 & g104
g116 = g103 & g105
g117 = g113 | c[45]
g118 = g114 | c[46]
g119 = g107 | g108 | c[51]
g120 = g109 | g110
g121 = g66 | g117 | c[47]
g122 = g68 | g118 | c[48]
g123 = g67 | g117 | c[49]
g124 = g69 | g118 | c[50]
g125 = ft.kofn(2, [g121, g123, g122, g124])
g126 = g111 | g112 | g125 | c[52]
g127 = g115 & g120
g128 = g116 & g120
g129 = g62 | g127 | c[53]
g130 = g63 | g128 | c[54]
g131 = g64 | g127 | c[55]
g132 = g65 | g128 | c[56]
g133 = g62 | g129 | c[57]
g134 = g63 | g130 | c[58]
g135 = g64 | g131 | c[59]
g136 = g65 | g132 | c[60]
g137 = ft.kofn(3, [g133, g134, g135, g136])
g138 = g106 | g119 | g137
g139 = g62 | g66 | g117 | g129 | c[47]
g140 = g63 | g68 | g118 | g130 | c[48]
g141 = g64 | g67 | g117 | g131 | c[49]
g142 = g65 | g69 | g118 | g132 | c[50]
g143 = g139 & g140 & g141 & g142
g144 = g111 | g112 | g143 | c[52]
top = g126 & g138 & g144

bdd = ft.getbdd(top)
print(bdd.count()) # The numbers of nodes and edges in the BDD

mcs = bdd.mcs() # Obtain the minimal cut sets from the BDD directly
print(mcs.extract())

prob = {
    'c0': 0.01,
    'c1': 0.051,
    'c2': 0.051,
    'c3': 0.051,
    'c4': 0.051,
    'c5': 0.112,
    'c6': 0.112,
    'c7': 0.112,
    'c8': 0.112,
    'c9': 0.016,
    'c10': 0.016,
    'c11': 0.016,
    'c12': 0.016,
    'c13': 0.0218,
    'c14': 0.0218,
    'c15': 0.0218,
    'c16': 0.0218,
    'c17': 0.015,
    'c18': 0.015,
    'c19': 0.015,
    'c20': 0.015,
    'c21': 0.016,
    'c22': 0.016,
    'c23': 0.016,
    'c24': 0.016,
    'c25': 0.015,
    'c26': 0.015,
    'c27': 0.015,
    'c28': 0.015,
    'c29': 0.0137,
    'c30': 0.0137,
    'c31': 0.0137,
    'c32': 0.0137,
    'c33': 0.016,
    'c34': 0.016,
    'c35': 0.016,
    'c36': 0.016,
    'c37': 0.016,
    'c38': 0.016,
    'c39': 0.016,
    'c40': 0.016,
    'c41': 0.0038,
    'c42': 0.0038,
    'c43': 0.0117,
    'c44': 0.0117,
    'c45': 0.00052,
    'c46': 0.00052,
    'c47': 0.018,
    'c48': 0.018,
    'c49': 0.018,
    'c50': 0.018,
    'c51': 0.000008,
    'c52': 0.000072,
    'c53': 0.015,
    'c54': 0.015,
    'c55': 0.015,
    'c56': 0.015,
    'c57': 0.0188,
    'c58': 0.0188,
    'c59': 0.0188,
    'c60': 0.0188
}

ft.prob(top, prob)

# Set the interval of the probability
error_lower = 0.5
error_upper = 1.5

prob = {
    'c0': (0.01 * error_lower, 0.01 * error_upper),
    'c1': (0.051 * error_lower, 0.051 * error_upper),
    'c2': (0.051 * error_lower, 0.051 * error_upper),
    'c3': (0.051 * error_lower, 0.051 * error_upper),
    'c4': (0.051 * error_lower, 0.051 * error_upper),
    'c5': (0.112 * error_lower, 0.112 * error_upper),
    'c6': (0.112 * error_lower, 0.112 * error_upper),
    'c7': (0.112 * error_lower, 0.112 * error_upper),
    'c8': (0.112 * error_lower, 0.112 * error_upper),
    'c9': (0.016 * error_lower, 0.016 * error_upper),
    'c10': (0.016 * error_lower, 0.016 * error_upper),
    'c11': (0.016 * error_lower, 0.016 * error_upper),
    'c12': (0.016 * error_lower, 0.016 * error_upper),
    'c13': (0.0218 * error_lower, 0.0218 * error_upper),
    'c14': (0.0218 * error_lower, 0.0218 * error_upper),
    'c15': (0.0218 * error_lower, 0.0218 * error_upper),
    'c16': (0.0218 * error_lower, 0.0218 * error_upper),
    'c17': (0.015 * error_lower, 0.015 * error_upper),
    'c18': (0.015 * error_lower, 0.015 * error_upper),
    'c19': (0.015 * error_lower, 0.015 * error_upper),
    'c20': (0.015 * error_lower, 0.015 * error_upper),
    'c21': (0.016 * error_lower, 0.016 * error_upper),
    'c22': (0.016 * error_lower, 0.016 * error_upper),
    'c23': (0.016 * error_lower, 0.016 * error_upper),
    'c24': (0.016 * error_lower, 0.016 * error_upper),
    'c25': (0.015 * error_lower, 0.015 * error_upper),
    'c26': (0.015 * error_lower, 0.015 * error_upper),
    'c27': (0.015 * error_lower, 0.015 * error_upper),
    'c28': (0.015 * error_lower, 0.015 * error_upper),
    'c29': (0.0137 * error_lower, 0.0137 * error_upper),
    'c30': (0.0137 * error_lower, 0.0137 * error_upper),
    'c31': (0.0137 * error_lower, 0.0137 * error_upper),
    'c32': (0.0137 * error_lower, 0.0137 * error_upper),
    'c33': (0.016 * error_lower, 0.016 * error_upper),
    'c34': (0.016 * error_lower, 0.016 * error_upper),
    'c35': (0.016 * error_lower, 0.016 * error_upper),
    'c36': (0.016 * error_lower, 0.016 * error_upper),
    'c37': (0.016 * error_lower, 0.016 * error_upper),
    'c38': (0.016 * error_lower, 0.016 * error_upper),
    'c39': (0.016 * error_lower, 0.016 * error_upper),
    'c40': (0.016 * error_lower, 0.016 * error_upper),
    'c41': (0.0038 * error_lower, 0.0038 * error_upper),
    'c42': (0.0038 * error_lower, 0.0038 * error_upper),
    'c43': (0.0117 * error_lower, 0.0117 * error_upper),
    'c44': (0.0117 * error_lower, 0.0117 * error_upper),
    'c45': (0.00052 * error_lower, 0.00052 * error_upper),
    'c46': (0.00052 * error_lower, 0.00052 * error_upper),
    'c47': (0.018 * error_lower, 0.018 * error_upper),
    'c48': (0.018 * error_lower, 0.018 * error_upper),
    'c49': (0.018 * error_lower, 0.018 * error_upper),
    'c50': (0.018 * error_lower, 0.018 * error_upper),
    'c51': (0.000008 * error_lower, 0.000008 * error_upper),
    'c52': (0.000072 * error_lower, 0.000072 * error_upper),
    'c53': (0.015 * error_lower, 0.015 * error_upper),
    'c54': (0.015 * error_lower, 0.015 * error_upper),
    'c55': (0.015 * error_lower, 0.015 * error_upper),
    'c56': (0.015 * error_lower, 0.015 * error_upper),
    'c57': (0.0188 * error_lower, 0.0188 * error_upper),
    'c58': (0.0188 * error_lower, 0.0188 * error_upper),
    'c59': (0.0188 * error_lower, 0.0188 * error_upper),
    'c60': (0.0188 * error_lower, 0.0188 * error_upper)
}

result = ft.prob_interval(top, prob)
print('lower: ', result.lower)
print('upper: ', result.upper)

TODO for fault tree analysis

  • FTA with MCS
  • Importance analysis
  • Sensitivity analysis
  • Uncertainty analysis; etc.

Multi-state system

Definition of Gate

MSS does not have default gates. Users need to define gates by themselves. The operation that can be used in the definition of a gate is as follows:

  • Arithmetic operations: +, -, *, /
  • Comparison operations: ==, !=, >, <, >=, <=
  • Logical operations:
    • mss.And: AND gate
    • mss.Or: OR gate
    • mss.Not: NOT gate
    • mss.switch: Switch-case structure
    • mss.case: Case structure
import relibmss as ms

# def for a gate with switch-case structure
def gate1(mss, x, y):
    return mss.switch([
        mss.case(cond=mss.And([x == 0, y == 0]), then=0),
        mss.case(cond=mss.Or([x == 0, y == 0]), then=1),
        mss.case(cond=mss.Or([x == 2, y == 2]), then=3),
        mss.case(cond=None, then=2) # default
    ])

Example of a multi-state system

import relibmss as ms

# Define gates
def gate1(mss, x, y):
    return mss.switch([
        mss.case(cond=mss.And([x == 0, y == 0]), then=0),
        mss.case(cond=mss.Or([x == 0, y == 0]), then=1),
        mss.case(cond=mss.Or([x == 2, y == 2]), then=3),
        mss.case(cond=None, then=2) # default
    ])

def gate2(mss, x, y):
    return mss.switch([
        mss.case(cond=x == 0, then=0),
        mss.case(cond=None, then=y)
    ])

mss = ms.MSS() # Context for the multi-state system

# Define variables

A = mss.defvar('A', 2) # 2 states
B = mss.defvar('B', 3) # 3 states
C = mss.defvar('C', 3) # 3 states

# Define a multi-state system
sx = gate1(mss, B, C)
ss = gate2(mss, A, sx)

# Define probabilities
prob = {
    'A': [0.1, 0.9],
    'B': [0.2, 0.3, 0.5],
    'C': [0.3, 0.4, 0.3]
}

# Calculate the probability
print(mss.prob(ss, prob))

Draw an MDD

import relibmss as ms

# Define gates
def gate1(mss, x, y):
    return mss.switch([
        mss.case(cond=mss.And([x == 0, y == 0]), then=0),
        mss.case(cond=mss.Or([x == 0, y == 0]), then=1),
        mss.case(cond=mss.Or([x == 2, y == 2]), then=3),
        mss.case(cond=None, then=2) # default
    ])

def gate2(mss, x, y):
    return mss.switch([
        mss.case(cond=x == 0, then=0),
        mss.case(cond=None, then=y)
    ])

mss = ms.MSS()

A = mss.defvar('A', 2)
B = mss.defvar('B', 3)
C = mss.defvar('C', 3)

# Define the order of variables
# this should be done before making MDD
mss.set_varorder({"A": 2, "B": 1, "C": 0})

sx = gate1(mss, B, C)
ss = gate2(mss, A, sx)

mdd = mss.getmdd(ss)
source = mdd.dot()

from graphviz import Source
from IPython.display import Image, display
Image(Source(source).pipe(format='png'))

Obtain the minimal vector sets

import relibmss as ms

# Define gates
def gate1(mss, x, y):
    return mss.switch([
        mss.case(cond=mss.And([x == 0, y == 0]), then=0),
        mss.case(cond=mss.Or([x == 0, y == 0]), then=1),
        mss.case(cond=mss.Or([x == 2, y == 2]), then=3),
        mss.case(cond=None, then=2) # default
    ])

def gate2(mss, x, y):
    return mss.switch([
        mss.case(cond=x == 0, then=0),
        mss.case(cond=None, then=y)
    ])

mss = ms.MSS()

A = mss.defvar('A', 2)
B = mss.defvar('B', 3)
C = mss.defvar('C', 3)

sx = gate1(mss, B, C)
ss = gate2(mss, A, sx)

mdd = mss.mvs(ss)
print(mdd.dot())

TODO

  • Add more examples
  • Add more functions for fault tree analysis
  • Add more functions for multi-state system analysis

License

MIT License

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

relibmss-0.4.1.tar.gz (19.7 kB view details)

Uploaded Source

Built Distribution

If you're not sure about the file name format, learn more about wheel file names.

relibmss-0.4.1-cp310-cp310-manylinux_2_34_x86_64.whl (424.4 kB view details)

Uploaded CPython 3.10manylinux: glibc 2.34+ x86-64

File details

Details for the file relibmss-0.4.1.tar.gz.

File metadata

  • Download URL: relibmss-0.4.1.tar.gz
  • Upload date:
  • Size: 19.7 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? No
  • Uploaded via: maturin/1.7.8

File hashes

Hashes for relibmss-0.4.1.tar.gz
Algorithm Hash digest
SHA256 78867cc3cc0e2b1ff3ee1da671635017280526c82575abe4dfb871caf3104da7
MD5 ba1b90773c16cf41d53f88c24e54ac08
BLAKE2b-256 17dd0c0e5cb77d142ab591c6446040f8e2271f38c24affdbe8a67555370a6c6a

See more details on using hashes here.

File details

Details for the file relibmss-0.4.1-cp310-cp310-manylinux_2_34_x86_64.whl.

File metadata

File hashes

Hashes for relibmss-0.4.1-cp310-cp310-manylinux_2_34_x86_64.whl
Algorithm Hash digest
SHA256 788b57d066a190d842a36dc770184fde3176c04e4f9094b3ac777b3386a5095f
MD5 49cbc428f2350ac250a8871f070221fb
BLAKE2b-256 ea42a2a1e954c1a0fc0945875e3ec4ac7859de5231777cc28749decb10a3c8d0

See more details on using hashes here.

Supported by

AWS Cloud computing and Security Sponsor Datadog Monitoring Depot Continuous Integration Fastly CDN Google Download Analytics Pingdom Monitoring Sentry Error logging StatusPage Status page