jobshop | Some jop shop scheduling algorithms
kandi X-RAY | jobshop Summary
kandi X-RAY | jobshop Summary
Some jop shop scheduling algorithms.
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- Generate genetic search template
- Compute the cost of a schedule
- Returns the lower bound for the given jobs
- Returns a random schedule
- Perform a simulatedAnnealing search
- Simulate anAnnealing
- Get the neighbors of a given state
- Get the neighbors of the given state
- Perform a random search
- Performs mutation on a subsequence
- Shuffle elements in x
- Select richard selection
- Select a population based on population size
- Read a list of jobs from a file
- Calculate the cost of a partial schedule
- Normalize jobs that are smaller than the given job
- Combine two jobs
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jobshop Examples and Code Snippets
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Trending Discussions on jobshop
QUESTION
I want to implement this simple jobshop example: https://developers.google.com/optimization/scheduling/job_shop
but in the old version of ORTools in C++ and I can't seem to find any support for the syntaxes in the older version. I have to write it in the old version to learn the syntaxes cause I have a bigger code that's written in the older version that I have to work on and I was hoping I could find an example that's written in the old version of ORTools to learn.
For example: a declaration of the solver in the new version:
_modelBuilder = new sat::CpModelBuilder();
and a declaration of the solver in the older version
_modelBuilder = new Solver("scheduler", parameters);
ANSWER
Answered 2021-Jan-29 at 10:27The old version can be found in earlier releases:
see here.
This being said
- it is no longer developed
- the CP-SAT version is much better.
QUESTION
I have a slightly updated jobshop problem code in which I added deadlines and idle_times (hope they're implemented correctly) thanks to the help of great users from this page. Now I'm looking to further update the code and also add another feature. Let's say it costs a lot to turn on a machine and give it a job so I need to introduce a penalty cost so that the solver tries to use that machine without having a pause time or idle time between orders since it would cost a lot to turn that machine back on again. Or at least try to have as little of an idle time as possible.
Any ideas how I could implement a feature like this? I was thinking of adding it either as a soft constraint or hard constraint but it only needs to be on certain machines. Let's say an oven that takes time and energy to turn it on again.
My code:
...ANSWER
Answered 2021-Jan-21 at 09:48Look at this example
This will create a set of literals, one for each possible direct successor of a task.
Now you can use this literal to create the penalty
QUESTION
I'm new to Google OR-Tools (and constraint programming in general) and I'm trying to add idle times to the Jobshop example.
The job-shop example I took can be found here: https://developers.google.com/optimization/scheduling/job_shop#entire-program
I made some modifications though as I included a deadline variable. Now the only thing I want to add to the program is an idle variable. For example, a machine that finishes a task has to have a certain idle time before starting on the next task. How could I implement this in the code? My code:
...ANSWER
Answered 2021-Jan-15 at 12:13You can just change this constraint:
QUESTION
I am working with a variant of the job shop problem where I wish to modify the task duration based on their assignment/rank in the machine schedule.
e.g. a simple case would be that the first task assigned on the machine will take 50% longer to complete.
A more general case would be that every nth task on a machine would require X% longer.
I have read about channelling constraints but I am not sure how to implement them in this scenario or if there are other better alternatives. Any direction would be much appreciated.
Below is the code I am using from or tools documentation for the job shop problem.
...ANSWER
Answered 2020-Aug-13 at 21:02Look at this constraint, it creates a circuit constraint that does the transitive reduction of precedences into a sequence of tasks.
Now you can use the start literal of each task to imply the correct duration
QUESTION
I have built a job shop scheduling algorithm using the ortools optimization library for python. the problem is when i made a flexible jobshop model with setup times it doesn't work and i think it is due to the arcs that i made, if there is anybody here who can explain more the circuit constraint, that would help me. By the way when i use a single machine it works.
Code:
...ANSWER
Answered 2020-Jun-02 at 12:02If a task is optional, you need to add a self looping arc on the node that corresponds to this arc.
So let's assume task_i with Boolean presence literal lit_i, you need to add
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Install jobshop
You can use jobshop like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.
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