logo
Tags down

shadow

How to define a constraint in Ortools to set a limit of distinct values


By : Julian Robert Teakle
Date : August 01 2020, 11:00 AM
I hope this helps you . For each value, create a boolean variable selected_value that is true iff at least one value is assigned to it.
For this you will need 2 sets of constraints:
code :
model.AddBoolOr([var_i_equals_value, ...]).OnlyEnforcedIf(selected_value)
for var_i_equals_value in ...:
    model.AddImplication(var_i_equals_value, selected_value)


Share : facebook icon twitter icon

Mysql select distinct but limit the distinct values


By : user3301912
Date : March 29 2020, 07:55 AM
it fixes the issue It sounds like you want the id values for three distinct columnx values. Is this right? Try this:
code :
SELECT id, columnx
FROM table AS t1
JOIN (
    SELECT DISTINCT(columnx) AS columnx
    LIMIT 1
) AS t2 ON (t1.columnx = t2.columnx);

Can I have a constraint on count of distinct values in a column in SQL?


By : Nachiket D
Date : March 29 2020, 07:55 AM
This might help you This cannot be done using a check constraint alone, but there is a way using a materialized view and a check constraint as I demonstrate here on my blog. For your example this would be:
code :
create materialized view emp_dep_mv
build immediate
refresh complete on commit as
select emp_id, count(*) cnt
from relatives
group by emp_id;

alter table emp_dep_mv
add constraint emp_dep_mv_chk
check (cnt <= 3)
deferrable;
alter table employees add num_relatives number(1,0) default 0 not null;

-- Populate for existing data
update employees
set num_relatives = (select count(*) from relatives r
                     where r.emp_id = e.emp_id)
where exists (select * from relatives r
              where r.emp_id = e.emp_id);

alter table employees add constraint emp_relatives_chk
check (num_relatives <= 3);

create trigger relatives_trg
after insert or update or delete on relatives
for each row
begin
   if inserting or updating then
      update employees
      set    num_relatives = num_relatives + 1
      where  emp_id = :new.emp_id;
   end if;
   if deleting or updating then
      update employees
      set    num_relatives = num_relatives - 1
      where  emp_id = :old.emp_id;
   end if;
end;

How do constraint optimization in OrTools with coefficents?


By : user1568571
Date : March 29 2020, 07:55 AM
To fix this issue I want to use ortools to generate all the possible combinations of a simple problem as in the following program. In this case I want x and y to be multiplications of 5 and additionally if start is 7, then the values of the x should be 7, 10, 15, 20, 25 and so on. How can I change following code for this?
code :
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from ortools.sat.python import cp_model


class VarArraySolutionPrinter(cp_model.CpSolverSolutionCallback):
  """Print intermediate solutions."""

  def __init__(self, variables):
    self.__variables = variables
    self.__solution_count = 0

  def NewSolution(self):
    self.__solution_count += 1
    for v in self.__variables:
      print('%s=%i' % (v, self.Value(v)), end=' ')
    print()

  def SolutionCount(self):
    return self.__solution_count


def mod_or_start():
  model = cp_model.CpModel()

  start = 7
  end = 20
  x = model.NewIntVar(start, end - 1, 'x')  # 8..19
  y = model.NewIntVar(start, end - 1, 'y')  # 8..19

  x_is_start = model.NewBoolVar('x_is_start')
  y_is_start = model.NewBoolVar('y_is_start')
  x_is_modulo_5 = model.NewBoolVar('x_is_modulo_5')
  y_is_modulo_5 = model.NewBoolVar('y_is_modulo_5')

  model.Add(x == start).OnlyEnforceIf(x_is_start)
  model.Add(y == start).OnlyEnforceIf(y_is_start)

  # Buggy.
  # model.AddModuloEquality(0, x, 5).OnlyEnforceIf(x_is_modulo_5)
  # model.AddModuloEquality(0, y, 5).OnlyEnforceIf(y_is_modulo_5)

  # Workaround until the modulo code is fixed.
  sub_x = model.NewIntVar(start // 5, end // 5, 'sub_x')
  sub_y = model.NewIntVar(start // 5, end // 5, 'sub_y')
  model.Add(x == 5 * sub_x).OnlyEnforceIf(x_is_modulo_5)
  model.Add(y == 5 * sub_y).OnlyEnforceIf(y_is_modulo_5)
  # Remove duplicate solutions
  model.Add(sub_x == start // 5).OnlyEnforceIf(x_is_modulo_5.Not())
  model.Add(sub_y == start // 5).OnlyEnforceIf(y_is_modulo_5.Not())

  # At least one option is true.
  model.AddBoolOr([x_is_start, x_is_modulo_5])
  model.AddBoolOr([y_is_start, y_is_modulo_5])

  # Create a solver and solve.
  solver = cp_model.CpSolver()
  solution_printer = VarArraySolutionPrinter([x, y])
  status = solver.SearchForAllSolutions(model, solution_printer)
  print('Status = %s' % solver.StatusName(status))
  print('Number of solutions found: %i' % solution_printer.SolutionCount())


mod_or_start()
x=15 y=15 
x=15 y=7 
x=10 y=7 
x=7 y=7 
x=7 y=15 
x=7 y=10 
x=10 y=15 
x=10 y=10 
x=15 y=10 
Status = FEASIBLE
Number of solutions found: 9

OR Tools Constraint that requires equility of variables [ortools]


By : preet
Date : March 29 2020, 07:55 AM
it helps some times I want create a linear solver model using OR-Tools. I have two numVars and one of my constraints is the equility of these two variables. But I could not find a way to set a constraint that takes a variable. I can do this with gurobi library. Below are the codes for both libraries. Is there a way to pass variables to both sides of a constraint such as xa==xb? in advance.
code :
from ortools.linear_solver import pywraplp
solver = pywraplp.Solver('SolveSimpleSystem', pywraplp.Solver.GLOP_LINEAR_PROGRAMMING)

# Create Variables
xa = solver.NumVar(0, solver.infinity(),'xa')
xb = solver.NumVar(0, solver.infinity(),'xb')

# production constraint
solver.Add(xa*400 + xb*300 >= 25000)
solver.Add(xa*300 + xb*400 >= 27000)
solver.Add(xa*200 + xb*500 >= 30000)
solver.Add(xa>=0)
solver.Add(xb>=0)
solver.Add(xa==xb)

solver.Minimize(xa * 20000 + xb * 25000)

solver.Solve()
print("Rafinery Solution:")
print("Rafinery A work days:", xa.solution_value())
print("Rafinery B work days:", xb.solution_value())
print("Cost : ", solver.Objective().Value())

why is the ORTOOLS guided local search, that starts with a feasible solution considered constraint programming?


By : user3169559
Date : March 29 2020, 07:55 AM
hope this fix your issue There are two reasons.
1) The initial solution heuristics is a combination of fast LS heuristic search and standard constraint programming search.
Related Posts Related Posts :
  • Camera not centre on player sprite (monogame)
  • How to set a default type for T in a static generic method?
  • How can I insert multiple items of data into SQL using Web API?
  • Finding longest time in an array
  • How to find two quotation marks in a string
  • X509Certificate2 certification issue
  • Image format change in Azure
  • Why is there such big time difference in searching for element with higher index in ConcurrentBag?
  • Async Lambda Issue
  • C# SSIS Script Task - Add Thousand Seperator when formatting Excel column
  • How to check if a textbox starts with numeric value
  • c# Strange Pairs || I can't spot the difference between these 2 solutions?
  • str.Split(".") not working in C# interactive window but work in C# .Net core project?
  • How to do 3 conditions with if else C#
  • merge two lists of same type in c#
  • Blazor - SortBy parameter for table column component
  • InvalidCastException: Specified cast is not valid Error when tried to fetch image from url
  • Search based on Properties
  • Ref string parameter is empty?
  • Make a class usable only from another class
  • C# WinForms ListBox changes selection to first item
  • How to replace various string occurrences in multiple strings the fastest way
  • C# async method called concurrently should wait for the first operation to complete
  • How to keep text at the top of console?
  • populate 2 lists using parallelism
  • ASP.NET C# MVC Entity Framework
  • How to set default value in Anonymous Class if any property is null;
  • How to get a string from c# code to XAML (WPF)
  • Application.Current is null, but new Application() still fails?
  • Clamp rigidbody2D Controller
  • Count number of child nodes for specific XML Node c#
  • How to sort where an object is added to based on it's attribute
  • Identify method to C#8 as a nullable checker?
  • How to connect to remote gRPC service
  • How can I debug MSMQ messages not arriving on a remote server?
  • Can a C# TPL dataflow propagate completion upstream?
  • Confusion regarding DataGridView CellValidation
  • Why do DependencyProperties need facade properties/getters/setters
  • Remove duplicated item with match from array
  • If-then statement to filter rows within data flow task
  • SqlDependency tries to do something with log4net and fails to start
  • Calling Microsoft Graph API using user context/user token C#
  • Creat matrix numbers from 1 to 64 with only one loop how can I do that?
  • await in async task method with synchronous logic c#
  • Async return Task method
  • Is there any way to make various types of enemies?
  • Should I create ViewModel for each View?
  • Delete one string value from string
  • Implementation details in Set properties in c# interfaces
  • C# async subsequent calls return existing task
  • Altering string variable storing xml in c#
  • ToAsyncEnumerable.ToList() throwing error after migrating the ef core to 3.1.0
  • How does one middleware call another?
  • The HTTP client does not redirect in the integration tests
  • Diagonal speed is too fast
  • how to get total count of 2nd/3rd inner list of object using Linq or lambda expression in c#
  • Disable button untill textbox & combobox are filled and selected
  • return 0 for items count in linq statement
  • Declaring multiple variables on one line
  • Real Time chart performance issue c# winform
  • shadow
    Privacy Policy - Terms - Contact Us © voile276.org