buy = {f: mdl.add_var(name=f) for f in dat.foods}
# Nutrition constraints
for c in dat.categories:
mdl.add_constraint(mdl.sum(dat.nutrition_quantities[f, c]["Quantity"] *
buy[f] for f in dat.foods) == nutrition[c],
name=c)
mdl.set_objective(mdl.sum(buy[f] * c["Cost"]
for f, c in dat.foods.items()))
if mdl.optimize():
sln = solution_schema.TicDat()
for f, x in buy.items():
if mdl.get_solution_value(x) > 0:
sln.buy_food[f] = mdl.get_solution_value(x)
for c, x in nutrition.items():
sln.consume_nutrition[c] = mdl.get_solution_value(x)
sln.parameters['Total Cost'] = sum(dat.foods[f]["Cost"] * r["Quantity"]
for f, r in sln.buy_food.items())
return sln
# ---------------------------------------------------------------------------------
# ------------------------ provide stand-alone functionality ----------------------
# when run from the command line, will read/write xls/csv/db/sql/mdb files
if __name__ == "__main__":
standard_main(input_schema, solution_schema, solve)
# ---------------------------------------------------------------------------------
class CogStopProgress(Progress):
def mip_progress(self, theme, lower_bound, upper_bound):
super(CogStopProgress, self).mip_progress(theme, lower_bound, upper_bound)
print("%s:%s:%s"%(theme.ljust(30), "Percent Error".ljust(20),
percent_error(lower_bound, upper_bound)))
# return False (to stop optimization) if the cog.stop file exists
return not os.path.exists("cog.stop")
# creating a single argument version of solve to pass to standard_main
def _solve(dat):
# create local text files for logging
with LogFile("output.txt") as out :
with LogFile("error.txt") as err :
solution = solve(dat, out, err, CogStopProgress())
if solution :
print('\n\nUpper Bound : %g' % solution.parameters["Upper Bound"]["value"])
print('Lower Bound : %g' % solution.parameters["Lower Bound"]["value"])
print('Percent Error : %s' % percent_error(solution.parameters["Lower Bound"]["value"],
solution.parameters["Upper Bound"]["value"]))
return solution
else :
print('\nNo solution')
standard_main(dataFactory, solutionFactory, _solve)
# ---------------------------------------------------------------------------------