def BuildConstraint6(solver, assignment_dict, var_dict):
for (work_date, name), fixed_shift in assignment_dict.items():
if fixed_shift is None:
continue
var_name = util.GetVariableName(name, str(work_date), fixed_shift.name)
if fixed_shift == data_types.ShiftType.OFF:
for work_shift_type in _WORK_SHIFT_NAMES:
work_var_name = util.GetVariableName(name, str(work_date),
work_shift_type)
solver.Add(var_dict[work_var_name] == 0)
else:
solver.Add(var_dict[var_name] == 1)
def BuildConstraint2(solver, person_config, all_date_strs, var_dict):
for i in range(len(all_date_strs) - 1):
work_date_str = all_date_strs[i]
next_date_str = all_date_strs[i + 1]
night_var = var_dict[util.GetVariableName(person_config.name,
work_date_str, _NIGHT_NAME)]
day_var = var_dict[util.GetVariableName(person_config.name,
next_date_str, _DAY_NAME)]
evening_var = var_dict[util.GetVariableName(person_config.name,
next_date_str,
_EVENING_NAME)]
solver.Add(night_var + day_var + evening_var <= 1)
def BuildConstraint1(solver, person_config, all_date_strs, var_dict):
for date_str in all_date_strs:
vars = []
for shift_type in _WORK_SHIFT_NAMES:
var_name = util.GetVariableName(person_config.name, date_str,
shift_type)
vars.append(var_dict[var_name])
solver.Add(util.VariableSum(vars) <= 1)
def BuildAllConstraints(software_config,
person_configs,
date_configs,
assignment_dict,
exclude_start=None,
exclude_end=None,
keep_offdates=False):
"""Returns (solver, var_dict)
assignment_dict: dict of (datetime.date, str) -> data_types.ShiftType, assignment dict
"""
solver = pywraplp.Solver('scheduling_program',
pywraplp.Solver.CBC_MIXED_INTEGER_PROGRAMMING)
var_dict = dict()
all_date_strs = list(
date_util.GenerateAllDateStrs(software_config.start_date,
software_config.end_date))
# When the schedule is to be updated partially
assignment_dict = getAssignmentsToFix(assignment_dict, exclude_start,
exclude_end, keep_offdates)
# Create variables
for work_date in all_date_strs:
for person_config in person_configs:
for shift_type_str in _WORK_SHIFT_NAMES:
var_name = util.GetVariableName(person_config.name, work_date,
shift_type_str)
var_dict[var_name] = solver.BoolVar(var_name)
# Create constraints 1-7
for person_config in person_configs:
# 1. only work one shift in one day
BuildConstraint1(solver, person_config, all_date_strs, var_dict)
# 2. After night shift, no work next day/evening
BuildConstraint2(solver, person_config, all_date_strs, var_dict)
# 3. no more than n consecutive workdays
BuildCosntraint3(solver, person_config, all_date_strs, var_dict)
# 4. no more than m consecutive nights
BuildConstraint4(solver, person_config, all_date_strs, var_dict)
# 5. Minimum a, maximum b total workdays
BuildConstraint5(solver, person_config, all_date_strs, var_dict)
# 6. No work on off-shifts & Work in predefined shift
BuildConstraint6(solver, assignment_dict, var_dict)
# 7. Match the number of workers in each shift
for date_config in date_configs:
BuildConstraint7(solver, person_configs, date_config, var_dict)
return (solver, var_dict)
def BuildConstraint5(solver, person_config, all_date_strs, var_dict):
vars = []
for date_str in all_date_strs:
for shift_type_str in _WORK_SHIFT_NAMES:
var_name = util.GetVariableName(person_config.name, date_str,
shift_type_str)
vars.append(var_dict[var_name])
var_sum = util.VariableSum(vars)
solver.Add(person_config.min_total_workdays <= var_sum)
solver.Add(var_sum <= person_config.max_total_workdays)
def BuildConstraint4(solver, person_config, all_date_strs, var_dict):
max_nights = person_config.max_consecutive_nights
for from_index in range(len(all_date_strs) - max_nights):
vars = []
for i in range(max_nights + 1):
var_name = util.GetVariableName(person_config.name,
all_date_strs[from_index + i],
_NIGHT_NAME)
vars.append(var_dict[var_name])
solver.Add(util.VariableSum(vars) <= max_nights)
def BuildCosntraint3(solver, person_config, all_date_strs, var_dict):
max_days = person_config.max_consecutive_workdays
for from_index in range(len(all_date_strs) - max_days):
vars = []
for i in range(max_days + 1):
for shift_type_str in _WORK_SHIFT_NAMES:
var_name = util.GetVariableName(person_config.name,
all_date_strs[from_index + i],
shift_type_str)
vars.append(var_dict[var_name])
solver.Add(util.VariableSum(vars) <= max_days)
def BuildConstraint7(solver, person_configs, date_config, var_dict):
date_str = str(date_config.work_date)
vars_day = []
vars_evening = []
vars_night = []
for person_config in person_configs:
var_name = util.GetVariableName(person_config.name, date_str,
_DAY_NAME)
vars_day.append(var_dict[var_name])
var_name = util.GetVariableName(person_config.name, date_str,
_EVENING_NAME)
vars_evening.append(var_dict[var_name])
var_name = util.GetVariableName(person_config.name, date_str,
_NIGHT_NAME)
vars_night.append(var_dict[var_name])
solver.Add(util.VariableSum(vars_day) == date_config.num_workers_day)
solver.Add(
util.VariableSum(vars_evening) == date_config.num_workers_evening)
solver.Add(util.VariableSum(vars_night) == date_config.num_workers_night)
def ToAssignmentDict(all_dates, names, var_dict):
assignment_dict = dict()
for name in names:
for work_date in all_dates:
has_work = False
for work_shift_type in data_types.ShiftType.WorkShiftTypes():
variable = var_dict[util.GetVariableName(
name, str(work_date), work_shift_type.name)]
# A work shift is assigned to the person on this date.
if variable.solution_value() == 1:
assignment_dict[(work_date, name)] = work_shift_type
has_work = True
break # There should be max 1 assignment that day, by constraint 1.
# Mark as 'OFF' if no work is found that day
if not has_work:
assignment_dict[(work_date, name)] = data_types.ShiftType.OFF
return assignment_dict