Questions tagged [pulp]
Questions relevant to the PuLP modelling framework in Python
63
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Detect presolve status in pulp model
Hi I am running a model using pulp CBC and have few constraints in the model that may make the model infeasible if wrong input is given to the model.
I can see while my model runs that in case of ...
1
vote
3
answers
178
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PuLp is ignoring all of the constraints given to it
I am trying to solve a portfolio optimization problem using PuLP where given a dictionary of stock tickers and their returns for the day, returns a set of weights for each stock such that portfolio ...
- 13
0
votes
1
answer
79
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applying a piecewise linearized equation in pulp
The background is I'm building a toy rent vs. buy mortgage calculator. I am an experienced software engineer but my math skills are 20 years behind me and I admit to being very lost.
I've been using ...
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3
votes
2
answers
228
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Binary Integer Programming Problem - Enforce Zeros on Certain Groups
I'm working on a binary integer programming problem using pulp. I have a vector X = [x_1, x_2, x_3, . . . , x_n]. I have enforced a number of simple constraints. I ...
- 33
2
votes
1
answer
80
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How to linearize the multiplication by a binary decision variable?
I am currently optimizing a hydrogen production chain.
I am optimizing the production regime, and the size of the required wind, solar and the electrolyser.
For every hour of the year, the production ...
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3
votes
1
answer
156
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Assignment Problem - Students and teachers
I ran across this problem at work and I'm sure that we can optimize it with OR.
I have $n(T) = 4$ teachers and $n(S) = 7$ students that should have a weekly individual class.
If a student $s$ has a ...
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1
vote
2
answers
138
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Efficient ways to do pairwise/multiplicative variables in integer linear programming on PuLP / Python
I'm trying to formulate an LP that is in essence a variant of the sudoku problem, and I've repurposed the code from https://coin-or.github.io/pulp/CaseStudies/a_sudoku_problem.html.
The differences ...
- 21
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3
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167
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Using PULP to model machines in a factory
Complete revision:
I have all 4 machines that can run in positive and negative directions which results in 2 outputs:
$ P_1 = \begin{cases}
-390 \le P_1 \le -300 & \text{for neg mode}\\
0 &...
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1
vote
3
answers
77
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PuLP ensure first and last choice
I have an assignment problem where I have $N$ locations and $M$ dates for each location, and the goal is to choose $K$ location-date pairs that maximize revenue. There are a number of constraints, for ...
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2
votes
3
answers
894
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Any Idea why PuLP is ignoring binary variables?
When I solve the following code, the binaries for the lines_selection variable is not respected by PuLP. Can anyone please point me out to the reason why this could ...
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-2
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1
answer
67
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Mixed Integer programming - Problem modelling coincidence restriction in scheduling match problem
I am trying to model and solve a problem for maximize audience of matches that must be scheduled in different slots (I am using python PulP library). Below I explain the problem and the model process ...
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4
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1
answer
205
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Understanding reduced costs and dual values
I have a headache regarding calculating the reduced costs of a linear program. I am using Pulp for modelling and CBC for solving.
What I do is, I model a linear programming problem based on a rhs ...
- 1,133
3
votes
2
answers
905
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Pulp problem gets the right objective value but fails to find the minimal solution
I converted an excel solver problem to Pulp. However, while the pulp program calculates the objective function value correctly, it doesn't arrive at the right answer. I can't figure out what is wrong ...
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1
vote
1
answer
278
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How to save log file from pulp , log including algorithms used by the solver?
How to save log file from pulp , log including algorithms used by the solver ?
while this is printed in the python IDE console, looking to save it as a txt file .
- 469
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192
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Problem of optimal solution generated with Pulp
I'm trying to use Pulp to solve VRP problem. Here is the model:
...
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-1
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1
answer
155
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Modeling a problem with python pulp transportation problem
I am trying to solve the following problem.
How to build a deterministic optimization model for the following fc
we have $x_1,x_2,...,x_365$ are the order shipped from an FC to a customer for 365 days
...
3
votes
2
answers
236
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Simple Integer Optimization Problem: docplex CP model works but equivalent PuLP+CBC model is infeasible?
I have an integer optimization problem with one constraint per decision variable and no objective function. It can be coded and solved using docplex, however I am ...
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2
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1
answer
50
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Split variables into groups, each constrained to hold a specific number of variables, while optimizing group sums towards specific values
I have a number of variables each assigned an integer value. I need to split these variables in three groups with a predefined number of variables going into each group while optimizing towards ...
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3
votes
2
answers
166
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Find all pivots that the simplex algorithm visited, i.e., the intermediate solutions, using Python
For my research, I am interested in finding the trajectory outlined by the pivots along the way of optimizing an LP problem, but I only know how to use Python PuLP to obtain the optimal solution. Is ...
- 31
0
votes
2
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128
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Inventory Continuity Equation
I have to minimize the inventory remaining at end of the period(28 days). Each item would perish after a fixed number of days and we can order items only on certain weekdays(M,T,S,S). Demand is ...
5
votes
1
answer
2k
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How to call HiGHS solver from python PuLP MIP?
I have a large MIP built with PuLP in python, and want to utilize the HiGHS Solver. However, PuLP does not have the option to use HiGHS as a solver. One option I am aware of would be to use PuLP to ...
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133
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Profit Optimization in Python with Difficult Constraints to Maximize Net Revenue
I am currently trying to work on this problem that determines the best constraints on how to place these 'bids'- please see the second column in the screenshot:
The ask at hand is to uncover a model ...
- 11
1
vote
1
answer
247
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PULP : Constraint violation - multiple of expected value
I am developing a linear programming model in PULP that sends material from Origin Facilities to Transfer and Final Treatment Facilities. The objective function is based on summing the transport and ...
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4
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1
answer
548
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Subtour elimination implementation (DFJ) using Python (PULP). While loop never exits
The simple test problem I'm trying to implement is
\begin{align}
\min &\quad c_{ij}x_{ij} \\
\text{s.t} &\quad \\
&\quad \sum_{j\in N}x_{ij} = 1, \quad i\in N\\
&\quad \sum_{i\...
- 207
3
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1
answer
1k
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How to formulate cumulative sum of LpVariable in Pulp Python
I have a Multiple product LP optimization problem in which the product(B1,B2,D) will be received in variable quantity with respect to date column.
The Optimizer should LP variable Output as Assy Out ...
3
votes
1
answer
582
views
How do I turn off preprocessing in pulp?
there is an inbuilt preprocessing in CBC solver , which affects the optimality of my solution , I get the optimal output by turning this off in command prompt . How do I turn this off using pulp ?
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-1
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185
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I'm trying to solve an OR problem written using pulp framework , with gurobi, in Linux , but I'm not able to solve it
I'm trying to solve an OR problem written using pulp framework , with gurobi, in Linux , but I'm not able to solve it . In windows,I use this command to use gurobi ,
...
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2
votes
2
answers
431
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Find the list with the fewest elements whose cumulative sum reaches threshold
I have a question with which I am stuck and would be very grateful for help:
I have multiple lists of non-negative numerical values (all of the same length)
I want to find the list with the lowest <...
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2
votes
1
answer
1k
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Defining Objective Function in PuLP
I have a binary variable $X_{ijk}$ which I have defined as the following :
...
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2
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525
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Designing a multi-commodity network flow optimizer
I'm trying to solve multi commodity multi source network flow optimization problem using Python-PuLP. Here is how my problem looks like:
The numbers on the arcs represent the order of priority a ...
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4
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2
answers
678
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Python Pulp - LpMinimize Not Returning Expected Output - Scheduling Problem
I'm working on my first pulp model and something isn't going quite right. It looks like it's close, but for some reason it is not respecting one of my constraints...
It's a scheduling problem and I am ...
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1
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1
answer
2k
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Pulp Python - How to define a constraint with different indexes of variables
I am new to modeling LP with Pulp in Python and I need some help with defining a constraint with multiple variables with different indexes. Please see below.
The constraint is defined on A, B, C ...
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3
votes
1
answer
3k
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Complicated constraint with logical operators in PuLP
I have an optimization problem that I am trying to solve with PuLP.
All the variables are Booleans.
The variables that are "selected" will be true, all others false.
Objective function is ...
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5
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1
answer
125
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How to transfer an optimization problem written with GUROBI (in python) in a grammar that can be readily solved with another solver?
Trying to use an opensource optimization tool in python (having used only gurobi for years) I see that the whole code (representing the optimization problem in pythonic language) must be written ...
6
votes
1
answer
795
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Python "Coffee Shop Scheduling Problem" - Scheduling Lunches/Breaks
I'm working on an employee scheduling program in python. Having never done this before, I've been researching different libraries that can be used to accomplish the task.
Unfortunately, none of the ...
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3
votes
1
answer
354
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Multi period inventory / reordering MILP in PULP
I'm trying to optimize reorder quantities for $n$ products over $m$ periods in PuLP. The total reorder quantity should fill a container. I've never worked with multiple periods before, and I can't get ...
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1
answer
2k
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2
votes
0
answers
123
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Seeking help in pulp scheduling problem
I have successfully implemented a program where I allocate N truck drivers to M gathering hubs for each one of the days of the ...
- 153
2
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1
answer
526
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Violation of specific constraint in Pulp
I have successfully implemented a program where I allocate N truck drivers to M gathering hubs for each one of the days of the ...
- 153
4
votes
2
answers
1k
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Scheduling optimisation constraint on consecutive shifts & consecutive night shifts (`python`)
I am trying to write a program to schedule a team of 8 individuals into shifts.
I want to know how to model that every individual must get at least one night shift break, and must not work two ...
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0
answers
80
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PuLP Python: How to linearize an inequality involving an integer variable
I am working on a Copper payables problem where the objective function is to maximise the sum of copper payable over a time period, T.
The total amount of payable tonnes i.e. what the customer will ...
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4
votes
1
answer
1k
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How to convert static variables into arrays for use with PuLP
I have the following code in Python and PuLP which uses static variables. I want to know how to solve the problem by converting all of the LpVariable parts into an array, as well as the constraints. ...
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3
votes
2
answers
2k
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How to generate multiple solutions to linear program in Python?
I recently posted a question here where I had written some Pyomo code to solve a simple linear program, however I feel the Operations Research platform is perhaps a better fit for this question. My ...
- 333
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2
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227
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How can I formulate an objective function that minimises the number of items required to solve a problem
I am currently trying to solve a problem where I need to minimise transport cost through the choice of vehicle (and how many of each choice) subject to a given demand.
The problem:
There are currently ...
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3
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0
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713
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How can I see the engine log when solving a LP using pulp (python)?
I wonder which command should I use to see how the steps the pulp solver is doing when solving a linear program.
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2
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1
answer
1k
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How can I assign an initial value to a variable in PuLP?
I am trying to solve a production problem and right now I need to assign an initial value to the inventory, and that value is given.
This is my definition of the inventory variable:
...
- 21
4
votes
1
answer
120
views
CBC stalling after approximately 10 seconds
I'm using CBC with PuLP to solve a small unit commitment problem. I'm finding that with certain combinations of input parameters, CBC simply stalls. With other input parameters, it solves, usually ...
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1
answer
239
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Optimized Production Planning & Scheduling
I want to create an optimized schedule and production to meet demand of four different buyers. I am starting with Pulp but not able to account for continuous production variable and discrete dispatch ...
1
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0
answers
131
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Resource constrained LP problem
I am working on Diet Allocation problem. Where we need to provide food piece for protein deficiency. The data is as below:
...
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4
votes
2
answers
667
views
Output of binary variable greater than one
I am working on a shipping demurrage problem that uses a binary variable to denote the date a specific vessel can be loaded (I have been kindly helped by Wesley on OR before with this).
I am confident ...
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