Assignments Introduction & Any Integer

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En provenance du cours de The University of Melbourne

Discrete Optimization

220 notes

The University of Melbourne

Discrete Optimization

220 notes

Tired of solving Sudokus by hand? This class teaches you how to solve complex search problems with discrete optimization concepts and algorithms, including constraint programming, local search, and mixed-integer programming. Optimization technology is ubiquitous in our society. It schedules planes and their crews, coordinates the production of steel, and organizes the transportation of iron ore from the mines to the ports. Optimization clears the day-ahead and real-time markets to deliver electricity to millions of people. It organizes kidney exchanges and cancer treatments and helps scientists understand the fundamental fabric of life, control complex chemical reactions, and design drugs that may benefit billions of individuals. This class is an introduction to discrete optimization and exposes students to some of the most fundamental concepts and algorithms in the field. It covers constraint programming, local search, and mixed-integer programming from their foundations to their applications for complex practical problems in areas such as scheduling, vehicle routing, supply-chain optimization, and resource allocation.

À partir de la leçon

Welcome

These lectures and readings give you an introduction to this course: its philosophy, organization, and load. They also tell you how the assignments are a significant part of the class. This week covers the common input/output organization of the assignments, how they are graded, and how to succeed in this class.

Assignments Introduction & Any Integer9:23

Rencontrer les enseignants

Professor Pascal Van Hentenryck
Dr. Carleton Coffrin
Adjunct Lecturer
Computing and Information Systems

Hi everyone I'm Carlton the co instructor for this course and

the key architect behind all of the automated grading systems.

In this lecture I'm going to tell you about the assignment architecture so

you can understand how it works.

And then will going to go over an extremely simple example,

the first assignment in this class.

It's not even an optimization problem.

All you have to do is submit an integer to the system and

then go check your feedback on Coursera.

So it's just incredibly simple.

It's like the hello world assignment of this course.

So at a high level, how do these assignments work?

First you're going to download a zip file, which is going to contain

a variety of information for you to start the assignment.

You're going to start coding a solution on your computer and

you're going to test it locally.

So you can make sure on your local machine that

it's producing the kind of results you expect.

When you're done testing locally, that's when you go and

you run the submission script.

And what the submission script does, is it runs your algorithm locally,

generates a solution.

And then sends it off to Coursera, where the grader processes it and

gives you feedback on the Coursera system.

And of course, you can iterate this process.

So, after you see your grades and your feedback,

you should go back to your solution and start coding up something different.

Test it locally and just repeat until you have the grades you want.

So how do you begin this process?

Well on the Coursera site,

there's a number of ways you can get to each assignment.

But there's an assignments tab on the left which just aggregates

all the assignments you need to do to pass the course.

There are other optional assignments that you'll find in the weeks breakdown but

those aren't covered here.

Now if you look, this will just be a list of assignments.

And you can click on each particular one to see the details of that assignment.

In this example, we're going to drill down on the first assignment,

which is called Any Integer and look at that one.

So when you drill down, this is what you see.

This is the Any Integer assignment page.

Now the most important thing on this page for

you at this point, is this gray box right here.

By clicking this box, you'll download a zip file, which contains

all of the information you need to understand and implement the assignment.

It's also important to note this how to submit block on the right, that's going to

come back later and be very important to how you do the submission process.

Another key thing to note here is that there's actually two tabs.

By default, you're in the Instructions view, but

there's also a My submission view, which we'll come back to later.

So, what's inside this zip file?

All of the assignments have a similar structure.

You're going to have a handout.pdf which

details all the instructions about each of the assignments.

It's fully self contained.

We also provide videos to give you a brief introduction to the assignments, but

you don't need them.

This handout is what you need.

There's also going to be a solver.py, this is where your algorithm will be built.

You can call other things, you can call the languages, but

the submission script needs them to be access through solver.py.

So you either put your implementation natively in Python here, or

call external binaries.

And just as an example,

solver.py will always include a trivial solution that we're providing for you.

So that you can see how the parsing of the files works, how the presentation of

the solution works, and a very trivial way of submitting a solution to the system.

Last but not least they'll be a submit.py which handles running your solver

on a few inputs.

And basically it'll run the solver on your local machine, wrap up the results,

send them off to Coursera over the Internet.

And that'll initiate the grading process.

In most of the assignments you'll have a data directory which

includes the input data for your testing.

But in this particular assignment you don't need any because it so simple.

So, for example, if you were to look at the handout.pdf for Any Integer,

it looks like this.

They all have a similar structure, where you have a problem statement,

description of what the assignment is.

The output format specification and the input format specification and so on.

So you can read this on your own.

Now lat's look inside of solver.py for the Any Integer solution.

By default it has this solve it method.

This is the most important thing, this is the block of code where the algorithm will

go when you're implementing your assignments.

By default it just returns 0

because that's kind of the trivial solution we're providing for you.

If I was a student I need to change this to be what I want it to be.

So my favorite is seven, so

I'm just going to return seven, it's a very beautiful number.

So, now I have set my any integer solution.

How do I test it on my local computer?

Well add the terminal, you use Python and you call it on solver.py.

As you can see the Python file has little main function that we can use for

testing the command line.

In this case it says, this subscript will submit the integer 7,

which is what I expect.

So on my local machine, it looks like everything is working fine.

So if you're happy with this, the next step is to actually try submitting this

solution to the grading system.

So what you're going to do is run python submit.py, and

this is going to bring up an interactive menu that's going to ask

you which parts of the assignment do you want to submit.

And then compute them and then submit them.

In this case, there's only one apart which is to send the integer to the system, so

there's the option of 1 or 0.

And in further assignments, there'll be many more options.

So in my case,

I'm going to hit the number 1 to say I want to just submit this single part.

And what you can see here is it says submitting 7.

That means it read that particular part of the assignment, i ran your algorithm and

it got the result 7.

And it's going to send the result 7 to Coursera.

There might be multiple of these blocks,

depending on how many assignments you submit.

But at the end of getting through all the parts of the assignment,

you will get to a final thing which is called Computations Complete.

This indicates that the local execution on your computer is done.

And now you're going to start trying to send those results to Corsara.

The first thing it'll do is prompt you for your user name,

which is actually an email address.

So, where did these credentials come for submitting the assignments?

Now we're back to the assignment page.

Now, in that how to submit block what you're going to see is a user,

the email that's connected with your Corsara account and

then a special password that is only for this assignment.

You should be careful, these passwords change for each assignment.

So make sure you get the right one.

Copy this information from this page and we go back to the menu.

If I enter those two credentials I have on the page,

you can see put in my user name and my submission token.

Now it's going to say connecting to Coursera, that's actually the point where

it makes the connection over the Internet to Coursera.

And it'll say submitting 1 of 1 parts,

that's because there's one part in this particular assignment.

If you were doing another one, it might say submitting 4 of 6 parts or

something like that.

Now if that Internet request is made successfully,

Coursera is going to give you a response.

In this case, it said your submission has been accepted and will be graded shortly.

That means the response is good, everything is going as planned.

Now, where do you get your grades and your feedback?

Once again, you go back to the Coursera platform, and

remember that each programming page has two tabs, the Instruction tabs,

and the My submission tab.

So now you can look in the My submission tab.

This tab is going to be a list of every time you submitted this assignment.

It's going to include absolutely every submission you've made.

You can click the little arrow on the left to expand and see

the details of why you've got a particular score when you submitted that assignment.

So in this case, you can see on the 27th of August I got 3 out of 10.

But I don't know why.

The reason is that I haven't shown the greater output.

So by clicking that little line that says show greater output,

then it's going to reveal another textbox.

Which gives you detailed information about why you got the grade you did

in the platform.

So for example, on the submission I made at August 27 at 3:08 PM,

I have shown the grader output.

And you can see the message from the grader submission output is correct, but

the value of 7 is insufficient, and so on and so forth.

And you can scroll left and right on this text box to see the full detailed message.

So yeah, you make sure you open these things and look at what they're saying.

Yeah, you have to click the show greater output.

So that's the basic overview of doing the first assignment.

Let me conclude with some final remarks.

Everything is provided in source code.

And that's because we want you to have an easy tool to use.

But we also want you to hack it and make it better and customise it for

your particular needs.

So please feel free to modify the scripts and do whatever is best for you.

And we'll also note that all of the infrastructure for this course is

open source, and it's available at github.com/discreteoptimization.

So we encourage you to fork that repository and make

full requests to contribute what great innovations you have on the course back so

that everyone can enjoy them.

Last but not least, have a lot of fun.

This is the easiest part of the course, so we hope you really enjoyed it and

it will just get more fun as things go on.

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