def _attempt_to_improve_var_bounds_one_hs(solver: pywraplp.Solver,
coefficient_part: str, is_leq: bool,
right_hand_side: str):
coefficient_part = coefficient_part.strip()
if re.match(_REGEXP_SINGLE_VAR_NAME_ALL, coefficient_part):
if is_leq:
solver.LookupVariable(coefficient_part).SetUb(
float(right_hand_side))
else:
solver.LookupVariable(coefficient_part).SetLb(
float(right_hand_side))
def _set_coefficients(solver: pywraplp.Solver, objective_or_constraint,
coefficient_part: str, line_nr: int, var_names: set):
# Strip the coefficient whitespace
remainder = coefficient_part.strip()
if len(remainder) == 0:
raise ValueError("No variables present in equation on line %d." %
line_nr)
# All variables found
var_names_found = set()
running_constant_sum = 0.0
had_at_least_one_variable = False
while len(remainder) != 0:
# Combination sign
coefficient = 1.0
combination_sign_match = re.search(r"^[-+]", remainder)
if combination_sign_match is not None:
if combination_sign_match.group() == "-":
coefficient = -1.0
remainder = remainder[1:].strip()
# Real sign
sign_match = re.search(r"^[-+]", remainder)
if sign_match is not None:
if sign_match.group() == "-":
coefficient = coefficient * -1.0
remainder = remainder[
1:] # There is no strip() here, as it must be directly in front of the mantissa
# Mantissa and exponent
mantissa_exp_match = re.search(r"^(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?",
remainder)
whitespace_after = False
if mantissa_exp_match is not None:
coefficient = coefficient * float(mantissa_exp_match.group())
remainder = remainder[mantissa_exp_match.span()[1]:]
stripped_remainder = remainder.strip()
if len(remainder) != len(stripped_remainder):
whitespace_after = True
remainder = stripped_remainder
# Variable name
var_name_match = re.search(_REGEXP_SINGLE_VAR_NAME_START, remainder)
if var_name_match is not None:
# It must have had at least one variable
had_at_least_one_variable = True
# Retrieve clean variable name
clean_var = var_name_match.group()
var_names.add(clean_var)
if clean_var in var_names_found:
raise ValueError(
"Variable \"%s\" found more than once on line %d." %
(clean_var, line_nr))
var_names_found.add(clean_var)
solver_var = solver.LookupVariable(clean_var)
if solver_var is None:
solver_var = solver.NumVar(-solver.infinity(),
solver.infinity(), clean_var)
# Set coefficient
objective_or_constraint.SetCoefficient(solver_var, coefficient)
# Strip what we matched
remainder = remainder[var_name_match.span()[1]:]
stripped_remainder = remainder.strip()
whitespace_after = False
if len(remainder) != len(stripped_remainder):
whitespace_after = True
remainder = stripped_remainder
elif mantissa_exp_match is None:
raise ValueError(
"Cannot process remainder coefficients of \"%s\" on line %d." %
(remainder, line_nr))
else:
running_constant_sum += coefficient
# At the end of each element there either:
# (a) Must be whitespace (e.g., x1 x2 <= 10)
# (b) The next combination sign (e.g., x1+x2 <= 10)
# (c) Or it was the last one, as such remainder is empty (e.g., x1 <= 10)
if len(remainder) != 0 and not whitespace_after and remainder[
0:1] != "-" and remainder[0:1] != "+":
raise ValueError(
"Unexpected next character \"%s\" on line %d (expected whitespace or "
"combination sign character)." % (remainder[0:1], line_nr))
# There must have been at least one variable
if not had_at_least_one_variable:
raise ValueError(
"Not a single variable present in the coefficients on line %d." %
line_nr)
return running_constant_sum
