PuLP is an open source linear programming package for python. PuLP can be installed using pip, instructions here.
In this notebook, we'll explore how to construct and solve the linear programming problem described in Part 1 using PuLP.
Apr 3, 2018 / Brian Bouterse / Pulp 2.16.0 is now available in the stable repositories: pulp-2-stable; pulp-stable; This release includes new features. Pulp 2.6.3 Pulp 2.6.3 is released with packages for Fedora 22 and Fedora 21. Support for Fedora 20 has been dropped. Please see theFedora lifecyclefor more detail. Bug Fixes This is a minor release which contains bug fixes forthese issues. 5.2.3 PADOUT(OutputValues) Address: 0x1A101008 Reset Value: 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0.
A brief reminder of our linear programming problem:
Pulp 2 5 3 X 4
We want to find the maximum solution to the objective function:
Pulp 2.6.3 Pulp 2.6.3 is released with packages for Fedora 22 and Fedora 21. Support for Fedora 20 has been dropped. Please see theFedora lifecyclefor more detail. Bug Fixes This is a minor release which contains bug fixes forthese issues. The pulp is the part in the center of a tooth made up of living connective tissue and cells called odontoblasts.The pulp is a part of the dentin–pulp complex (endodontium). The vitality of the dentin-pulp complex, both during health and after injury, depends on pulp cell activity and the signaling processes that regulate the cell's behavior.
$Z = 4x + 3y$
Subject to the following constraints:
$
x geq 0
y geq 2
2y leq 25 – x
4y geq 2x – 8
y leq 2x -5
$
Then instantiate a problem class, we'll name it 'My LP problem' and we're looking for an optimal maximum so we use LpMaximize
We then model our decision variables using the LpVariable class. In our example, x had a lower bound of 0 and y had a lower bound of 2.
Upper bounds can be assigned using the upBound parameter.
The objective function and constraints are added using the += operator to our model.
The objective function is added first, then the individual constraints.
Boom 2: the best audio enhancement app 1 3. We have now constructed our problem and can have a look at it.
PuLP supports open source linear programming solvers such as CBC and GLPK, as well as commercial solvers such as Gurobi and IBM's CPLEX.
The default solver is CBC, which comes packaged with PuLP upon installation.
For most applications, the open source CBC from COIN-OR will be enough for most simple linear programming optimisation algorithms.
We have also checked the status of the solver, there are 5 status codes:
- Not Solved: Status prior to solving the problem.
- Optimal: An optimal solution has been found.
- Infeasible: There are no feasible solutions (e.g. if you set the constraints x <= 1 and x >=2).
- Unbounded: The constraints are not bounded, maximising the solution will tend towards infinity (e.g. if the only constraint was x >= 3).
- Undefined: The optimal solution may exist but may not have been found.
We can now view our maximal variable values and the maximum value of Z.
We can use the varValue method to retrieve the values of our variables x and y, and the pulp.value function to view the maximum value of the objective function.
Same values as our manual calculations in part 1.
In the next part we'll be looking at a more real world problem.
Introduction
Part 1 – Introduction to Linear Programming
Part 2 – Introduction to PuLP
Part 3 – Real world examples – Resourcing Problem
Part 4 – Real world examples – Blending Problem
Part 5 – Using PuLP with pandas and binary constraints to solve a scheduling problem
Part 6 – Mocking conditional statements using binary constraints
Using PuLP with pandas and binary constraints to solve a scheduling problem
In this example, we'll be solving a scheduling problem. We have 2 offshore production plants in 2 locations and an estimated demand for our products.
De word a pdf. We want to produce a schedule of production from both plants that meets our demand with the lowest cost.
A factory can be in 2 states:
- Off – Producing zero units
- On – Producing between its minimum and maximum production capacities
Both factories have fixed costs, that are incurred as long as the factory is on, and variable costs, a cost per unit of production. These vary month by month.
We also know that factory B is down for maintenance in month 5.
We'll start by importing our data.
Max_Capacity | Min_Capacity | Variable_Costs | Fixed_Costs | ||
---|---|---|---|---|---|
Month | Factory | ||||
1 | A | 100000 | 20000 | 10 | 500 |
B | 50000 | 20000 | 5 | 600 | |
2 | A | 110000 | 20000 | 11 | 500 |
B | 55000 | 20000 | 4 | 600 | |
3 | A | 120000 | 20000 | 12 | 500 |
B | 60000 | 20000 | 3 | 600 | |
4 | A | 145000 | 20000 | 9 | 500 |
B | 100000 | 20000 | 5 | 600 | |
5 | A | 160000 | 20000 | 8 | 500 |
B | 0 | 0 | 0 | 0 | |
6 | A | 140000 | 20000 | 8 | 500 |
B | 70000 | 20000 | 6 | 600 | |
7 | A | 155000 | 20000 | 5 | 500 |
B | 60000 | 20000 | 4 | 600 | |
8 | A | 200000 | 20000 | 7 | 500 |
B | 100000 | 20000 | 6 | 600 | |
9 | A | 210000 | 20000 | 9 | 500 |
B | 100000 | 20000 | 8 | 600 | |
10 | A | 197000 | 20000 | 10 | 500 |
B | 100000 | 20000 | 11 | 600 | |
11 | A | 80000 | 20000 | 8 | 500 |
B | 120000 | 20000 | 10 | 600 | |
12 | A | 150000 | 20000 | 8 | 500 |
B | 150000 | 20000 | 12 | 600 |
Demand | |
---|---|
Month | |
1 | 120000 |
2 | 100000 |
3 | 130000 |
4 | 130000 |
5 | 140000 |
6 | 130000 |
7 | 150000 |
8 | 170000 |
9 | 200000 |
10 | 190000 |
11 | 140000 |
12 | 100000 |
As we have fixed costs and variable costs, we'll need to model both production and the status of the factory i.e. whether it is on or off.
Production is modelled as an integer variable. Stronghold 3 gold edition download.
We have a value for production for each month for each factory, this is given by the tuples of our multi-index pandas DataFrame index.
Factory status is modelled as a binary variable. It will have a value of 1 if the factory is on and a value of 0 when the factory is off.
Binary variables are the same as integer variables but constrained to be >= 0 and <=1
Again this has a value for each month for each factory, again given by the index of our DataFrame
We instantiate our model and use LpMinimize as the aim is to minimise costs.
In our objective function we include our 2 costs:
- Our variable costs is the product of the variable costs per unit and production
- Our fixed costs is the factory status – 1 (on) or 0 (off) – multiplied by the fixed cost of production
An issue we run into here is that in linear programming we can't use conditional constraints.
For example we can't add to our model that if the factory is off factory status must be 0, and if it is on factory status must be 1. Before we've solved our model though, we don't know if the factory will be on or off in a given month.
Starcraft 2 for xbox. In this case construct constraints that have minimum and maximum capacities that are constant variables, which we multiply by the factory status.
Now, either factory status is 0 and: https://9cascithanegq.wixsite.com/bitesoftware/post/color-wheel-7-1-7-64.
- $ text{min_production} geq 0$
- $ text{max_production} leq 0$
Or factory status is 1 and:
- $ text{min_production} leq text{min_capacity}$
- $ text{max_production} leq text{max_capacity}$
(In some cases we can use linear constraints to model conditional statements, we'll explore this in part 6)
Let's take a look at the optimal production schedule output for each month from each factory. For ease of viewing we'll output the data to a pandas DataFrame.
Factory Status | Production | ||
---|---|---|---|
Month | Factory | ||
1 | A | 1 | 70000 |
B | 1 | 50000 | |
2 | A | 1 | 45000 |
B | 1 | 55000 | |
3 | A | 1 | 70000 |
B | 1 | 60000 | |
4 | A | 1 | 30000 |
B | 1 | 100000 | |
5 | A | 1 | 140000 |
B | 0 | 0 | |
6 | A | 1 | 60000 |
B | 1 | 70000 | |
7 | A | 1 | 90000 |
B | 1 | 60000 | |
8 | A | 1 | 70000 |
B | 1 | 100000 | |
9 | A | 1 | 100000 |
B | 1 | 100000 | |
10 | A | 1 | 190000 |
B | 0 | 0 | |
11 | A | 1 | 80000 |
B | 1 | 60000 | |
12 | A | 1 | 100000 |
B | 0 | 0 |
Pulp 2 5 3 X 2
Pulp 2 5 3 X 4
We want to find the maximum solution to the objective function:
Pulp 2.6.3 Pulp 2.6.3 is released with packages for Fedora 22 and Fedora 21. Support for Fedora 20 has been dropped. Please see theFedora lifecyclefor more detail. Bug Fixes This is a minor release which contains bug fixes forthese issues. The pulp is the part in the center of a tooth made up of living connective tissue and cells called odontoblasts.The pulp is a part of the dentin–pulp complex (endodontium). The vitality of the dentin-pulp complex, both during health and after injury, depends on pulp cell activity and the signaling processes that regulate the cell's behavior.
$Z = 4x + 3y$
Subject to the following constraints:
$
x geq 0
y geq 2
2y leq 25 – x
4y geq 2x – 8
y leq 2x -5
$
Then instantiate a problem class, we'll name it 'My LP problem' and we're looking for an optimal maximum so we use LpMaximize
We then model our decision variables using the LpVariable class. In our example, x had a lower bound of 0 and y had a lower bound of 2.
Upper bounds can be assigned using the upBound parameter.
The objective function and constraints are added using the += operator to our model.
The objective function is added first, then the individual constraints.
Boom 2: the best audio enhancement app 1 3. We have now constructed our problem and can have a look at it.
PuLP supports open source linear programming solvers such as CBC and GLPK, as well as commercial solvers such as Gurobi and IBM's CPLEX.
The default solver is CBC, which comes packaged with PuLP upon installation.
For most applications, the open source CBC from COIN-OR will be enough for most simple linear programming optimisation algorithms.
We have also checked the status of the solver, there are 5 status codes:
- Not Solved: Status prior to solving the problem.
- Optimal: An optimal solution has been found.
- Infeasible: There are no feasible solutions (e.g. if you set the constraints x <= 1 and x >=2).
- Unbounded: The constraints are not bounded, maximising the solution will tend towards infinity (e.g. if the only constraint was x >= 3).
- Undefined: The optimal solution may exist but may not have been found.
We can now view our maximal variable values and the maximum value of Z.
We can use the varValue method to retrieve the values of our variables x and y, and the pulp.value function to view the maximum value of the objective function.
Same values as our manual calculations in part 1.
In the next part we'll be looking at a more real world problem.
Introduction
Part 1 – Introduction to Linear Programming
Part 2 – Introduction to PuLP
Part 3 – Real world examples – Resourcing Problem
Part 4 – Real world examples – Blending Problem
Part 5 – Using PuLP with pandas and binary constraints to solve a scheduling problem
Part 6 – Mocking conditional statements using binary constraints
Using PuLP with pandas and binary constraints to solve a scheduling problem
In this example, we'll be solving a scheduling problem. We have 2 offshore production plants in 2 locations and an estimated demand for our products.
De word a pdf. We want to produce a schedule of production from both plants that meets our demand with the lowest cost.
A factory can be in 2 states:
- Off – Producing zero units
- On – Producing between its minimum and maximum production capacities
Both factories have fixed costs, that are incurred as long as the factory is on, and variable costs, a cost per unit of production. These vary month by month.
We also know that factory B is down for maintenance in month 5.
We'll start by importing our data.
Max_Capacity | Min_Capacity | Variable_Costs | Fixed_Costs | ||
---|---|---|---|---|---|
Month | Factory | ||||
1 | A | 100000 | 20000 | 10 | 500 |
B | 50000 | 20000 | 5 | 600 | |
2 | A | 110000 | 20000 | 11 | 500 |
B | 55000 | 20000 | 4 | 600 | |
3 | A | 120000 | 20000 | 12 | 500 |
B | 60000 | 20000 | 3 | 600 | |
4 | A | 145000 | 20000 | 9 | 500 |
B | 100000 | 20000 | 5 | 600 | |
5 | A | 160000 | 20000 | 8 | 500 |
B | 0 | 0 | 0 | 0 | |
6 | A | 140000 | 20000 | 8 | 500 |
B | 70000 | 20000 | 6 | 600 | |
7 | A | 155000 | 20000 | 5 | 500 |
B | 60000 | 20000 | 4 | 600 | |
8 | A | 200000 | 20000 | 7 | 500 |
B | 100000 | 20000 | 6 | 600 | |
9 | A | 210000 | 20000 | 9 | 500 |
B | 100000 | 20000 | 8 | 600 | |
10 | A | 197000 | 20000 | 10 | 500 |
B | 100000 | 20000 | 11 | 600 | |
11 | A | 80000 | 20000 | 8 | 500 |
B | 120000 | 20000 | 10 | 600 | |
12 | A | 150000 | 20000 | 8 | 500 |
B | 150000 | 20000 | 12 | 600 |
Demand | |
---|---|
Month | |
1 | 120000 |
2 | 100000 |
3 | 130000 |
4 | 130000 |
5 | 140000 |
6 | 130000 |
7 | 150000 |
8 | 170000 |
9 | 200000 |
10 | 190000 |
11 | 140000 |
12 | 100000 |
As we have fixed costs and variable costs, we'll need to model both production and the status of the factory i.e. whether it is on or off.
Production is modelled as an integer variable. Stronghold 3 gold edition download.
We have a value for production for each month for each factory, this is given by the tuples of our multi-index pandas DataFrame index.
Factory status is modelled as a binary variable. It will have a value of 1 if the factory is on and a value of 0 when the factory is off.
Binary variables are the same as integer variables but constrained to be >= 0 and <=1
Again this has a value for each month for each factory, again given by the index of our DataFrame
We instantiate our model and use LpMinimize as the aim is to minimise costs.
In our objective function we include our 2 costs:
- Our variable costs is the product of the variable costs per unit and production
- Our fixed costs is the factory status – 1 (on) or 0 (off) – multiplied by the fixed cost of production
An issue we run into here is that in linear programming we can't use conditional constraints.
For example we can't add to our model that if the factory is off factory status must be 0, and if it is on factory status must be 1. Before we've solved our model though, we don't know if the factory will be on or off in a given month.
Starcraft 2 for xbox. In this case construct constraints that have minimum and maximum capacities that are constant variables, which we multiply by the factory status.
Now, either factory status is 0 and: https://9cascithanegq.wixsite.com/bitesoftware/post/color-wheel-7-1-7-64.
- $ text{min_production} geq 0$
- $ text{max_production} leq 0$
Or factory status is 1 and:
- $ text{min_production} leq text{min_capacity}$
- $ text{max_production} leq text{max_capacity}$
(In some cases we can use linear constraints to model conditional statements, we'll explore this in part 6)
Let's take a look at the optimal production schedule output for each month from each factory. For ease of viewing we'll output the data to a pandas DataFrame.
Factory Status | Production | ||
---|---|---|---|
Month | Factory | ||
1 | A | 1 | 70000 |
B | 1 | 50000 | |
2 | A | 1 | 45000 |
B | 1 | 55000 | |
3 | A | 1 | 70000 |
B | 1 | 60000 | |
4 | A | 1 | 30000 |
B | 1 | 100000 | |
5 | A | 1 | 140000 |
B | 0 | 0 | |
6 | A | 1 | 60000 |
B | 1 | 70000 | |
7 | A | 1 | 90000 |
B | 1 | 60000 | |
8 | A | 1 | 70000 |
B | 1 | 100000 | |
9 | A | 1 | 100000 |
B | 1 | 100000 | |
10 | A | 1 | 190000 |
B | 0 | 0 | |
11 | A | 1 | 80000 |
B | 1 | 60000 | |
12 | A | 1 | 100000 |
B | 0 | 0 |
Pulp 2 5 3 X 2
Notice above that the factory status is 0 when not producing and 1 when it is producing
Pulp 2 5 3 Equals
Memory cleaner 4pda. Introduction
Part 1 – Introduction to Linear Programming
Part 2 – Introduction to PuLP
Part 3 – Real world examples – Resourcing Problem
Part 4 – Real world examples – Blending Problem
Part 5 – Using PuLP with pandas and binary constraints to solve a scheduling problem
Part 6 – Mocking conditional statements using binary constraints