Files
Transportation_Problem/main.py
T

176 lines
3.6 KiB
Python

import numpy as np
from typing import Optional
from enum import Enum
# M constant
M = 1_000_000
class State(Enum):
SOLVED = 0
UNSOLVED = 1
UNAPPLICABLE = 2
class Result:
solved: State
objective_function_value: Optional[np.int64]
solution: Optional[np.array]
def __init__(self,
solved: State,
objective_function_value: Optional[np.array] = None,
solution: np.int64 = None):
self.solved = solved
self.objective_function_value = objective_function_value
self.solution = solution
def NorthwestCorner(
S: np.array,
C: np.array,
D: np.array) -> Result:
# TODO Northwest corner method
pass
S = np.array([1, 2, 3, 4])
C = np.array([
[16, 16, 13, 22, 17],
[14, 14, 13, 19, 15],
[19, 19, 20, 23, M ],
[M, 0, M, 0, 0]])
D = np.array([30, 20, 70, 30, 60])
def Vogel(
S: np.array,
C: np.array,
D: np.array) -> Result:
C_length = len(C[0])
C_height = len(C)
#print(C_length)
#print(C_height)
RowD = np.array
ColD = np.array
RowD = np.resize(RowD, C_height)
ColD = np.resize(ColD, C_length)
#print(sorted(C[0]))
#print(sorted(C[0])[0])
#print(sorted(C[0])[1])
#Finding differences
for y in range(C_height):
RowD[y] = abs(sorted(C[y])[0] - sorted(C[y])[1])
for x in range(C_length):
ColD[x] = abs(sorted(C.T[x])[0] - sorted(C.T[x])[1])
#print(RowD)
#print(ColD)
#Maximum difference
maxD = max(np.concatenate((ColD, RowD)))
#print(maxD)
# TODO Vogel's method
pass
Vogel(S,C,D)
def Russell(
S: np.array,
C: np.array,
D: np.array) -> Result:
selected = np.zeros(C.shape)
remaining_rows = np.ones(C.shape[0], dtype=bool)
remaining_cols = np.ones(C.shape[1], dtype=bool)
x_0 = np.zeros(C.shape)
while True:
mask = np.outer(remaining_rows, remaining_cols)
u = np.max(np.where(mask, C, -M), axis=1)
v = np.max(np.where(mask, C, -M), axis=0)
d = np.zeros(C.shape, dtype=np.int64)
for i in range(C.shape[0]):
for j in range(C.shape[1]):
if selected[i][j]:
d[i][j] = M
else:
d[i][j] = C[i][j] - u[i] - v[j]
i, j = np.unravel_index(np.argmin(d, axis=None), d.shape)
if (D[j] == 0):
break
if (S[i] >= D[j]):
x_0[i][j] = D[j]
S[i] -= D[j]
D[j] = 0
remaining_cols[j] = 0
else:
x_0[i][j] = S[i]
D[j] -= S[i]
S[i] = 0
remaining_rows[i] = 0
selected[i][j] = 1
return x_0
def print_problem_statement(S, C, D) -> None:
# TODO print table
pass
def solve(
S: np.array,
C: np.array,
D: np.array) -> int:
print_problem_statement(S, C, D)
if (np.sum(S) != np.sum(D)):
print("The problem is not balanced!")
return 1
result1 = NorthwestCorner(S, C, D)
result2 = Vogel(S, C, D)
result3 = Russell(S, C, D)
# TODO check for state (unappicable?)
print(result1.solution, result2.solution, result3.solution)
return 0
if __name__ == "__main__":
C = np.array([
[16, 16, 13, 22, 17],
[14, 14, 13, 19, 15],
[19, 19, 20, 23, M],
[M, 0, M, 0, 0]
], dtype=np.int64)
S = np.array([
50, 60, 50, 50
])
D = np.array([
30, 20, 70, 30, 60
])
print(Russell(S, C, D))