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In this lecture I'm going to talk about Jupiter notebook.

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Occasionally I get this strange question from students asking why I don't do things in Jupiter or notebook.

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Let me explain why I think this is strange.

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Firstly it's my position that it's completely unnecessary and actually doesn't change anything.

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To use Jupiter notebook or not.

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Let me repeat that using Jupiter notebook is exactly the same as not using Jupiter notebook.

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There's no difference other than the fact that it looks different.

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In other words the screen is a different color.

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Obviously such a difference is trivial in this lecture.

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I'm going to demonstrate how that's the case

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one major reason I dislike Jupiter notebook is because it causes too many students to be unaware of

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how Python really works.

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If you're only comfortable inside notebook and when you see Python code in a text file or anywhere else

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and you get scared or intimidated that's not good.

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That Python code that's in the text file is exactly the same as what would be in the notebook.

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There's really nothing scary about it.

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Programmers working at real jobs eventually need to write code that's going to be deployed and run automatically.

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In other words your final code is going to sit in a python file that runs by itself without you put

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a notebook.

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So if you're going to have any hope of using these skills in a real job you had better be comfortable

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with writing Python code outside of Jupiter notebook.

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You would also better be aware that there is actually zero difference between writing code in a Jupiter

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a notebook and writing code in Python or the console

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here's one example I like of how you might use python in the quote unquote real world.

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Let's say you write a script that e-mails your boss to tell him you're going to be late for work and

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let's say you don't actually want to send this email manually but you want it to get sent automatically

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every Friday morning so that your boss doesn't yell at you for coming into work late after you a party

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too hard.

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Thursday night.

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Well that's very simple.

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All I have to do is on my server create what's called a cron tab in it.

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I just enter the code for when I want this command to run and then to the right of that I specify the

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command that I want to run.

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That's just Python space.

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And then the script name as you can see it's simply how you would run this python scripts from the command

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line.

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And now every Friday at nine forty five a.m. This script is going to send the same email to your boss.

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Tell him you'll be late.

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Well let's not get off track here.

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The point of this is you really don't want to be using Jupiter notebook for something like this.

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I think one perceived advantage of Jupiter notebook is that you can see the results of intermediate

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calculations.

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However this is merely a perceived advantage and not a real advantage because you can do the exact same

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thing even when you're not inside notebook firstly as I'm sure you've seen by now.

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I Python also prints out the results after you enter a command.

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I python is called a repo which stands for read Val print loop and that's generally what they all do.

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No matter what language you're in so whether that's Python Ruby HP or any other language.

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The keyword here is print.

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Why is that.

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Well one of my golden rules for writing and debugging code is When in doubt print it out.

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I can't tell you how many times I've gotten a question on the Q and A when it could have been easily

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answered by inserting a print statement into the existing code

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anyway.

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What's the point of this long discussion about printing things out.

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Well it's that if you think Jupiter notebook is the only program that helps you do this you need to

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expand your horizons a little bit.

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You should in fact always be doing this if you're not using an abundant amount of print statements while

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coding you are not doing it right.

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Remember programming is not philosophy.

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You're not supposed to be running a program in your head.

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That's like trying to do long division in your head when you have a calculator in your hand so just

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by printing things out you can be more efficient.

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Stop trying to guess what a program will do and just let the program itself tell you what it's doing.

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The key takeaway here is you should always be printing things out.

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The fact that Jupiter notebook shows you the result of each block of code is not simply a happy surprise

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but another important lesson here is that if you want to use Jupiter notebook there is absolutely nothing

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stopping you from doing so.

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In other words using Jupiter notebook is 100 percent compatible with everything we are already doing.

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In fact if you recall your goal in these courses is not to run my code but to write your own code and

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of course since it's your code you can write a however you want including Jupiter notebook in the rest

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of his lecture.

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I'm going to prove to you that you can take any scripts from our course repository which we know runs

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in the console because that's how I always demonstrate it and show you that this exact same code runs

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in Jupiter notebook.

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Let's begin

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OK.

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So let's say I'm in the folder num pi class and I'm interested in the code inside.

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Classification example that pi as you can see what I have right now is this code inside a text editor.

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Now if you're not aware of what a text editor is it's just a program that shows you the contents of

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a text file and lets you edit those contents.

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It's the ideal program for writing code.

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Now occasionally if you're writing in a language like Java or swift you might want to use an idea.

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But even then it's totally optional.

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These days I prefer to write Java in a plain text editor like sublime text as well.

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In any case normally one does not need to use an idea for writing Python code.

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Now about Jupiter notebook.

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Well let's start up a Jupiter notebook so I'm gonna go Jupiter notebook.

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All right.

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So now I've got Jupiter notebook running so I'm going to start a new notebook.

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Also notice that we started the notebook in the same directory as the relevant python file so that's

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something you want to keep in mind for the future now at this point.

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What I'm going to do is I'm going to prove that everything in this python file works exactly the same

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in the notebook as it does in the console.

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So let's start with the inputs let's grab this one to

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all right paste that in run it so everything's fine so far.

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Now let's load in the data.

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We've loaded in the data.

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Now I'm not sure what its type is.

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So I can check it by using the type function.

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So let me try that

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cool so I get SDK learned that you tells that bunch.

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So that's the type of the variable data now.

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Previously you recall that we did this example in Python but as you can see the result is the same and

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you put a notebook alternatively if you wanted to run this python file in the console so you wanted

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to type let's say

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so let's say you wanted to type in Python classification example that pi then you could just add some

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print statements if you wanted to show those same lines while this file was running.

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Now I'm not going to go through such elaborate detail for the rest of this example since you've already

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seen it.

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So let's just get through the rest line by line

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let's say I want to check out the keys in the data variable OK looks good so far.

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Let's check the shape of the data actually be ok.

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Looks good so far.

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Check the target's

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still.

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What we expect the target names.

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Looks good

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target shape.

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It should be five sixty nine.

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Yeah let's check out the feature names

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OK.

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That's the same as well.

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Now let's do our train test split

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OK.

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Now let's instantiate and fit our model

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all right.

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Now let's check the train score

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and the test score.

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All right now let's see how we can make new predictions

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S.C. how if you assign to a variable it doesn't print the result but if you have an expression then

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it does print the result.

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So there are some predictions and this was an alternative way to calculate the accuracy of the predictions.

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So we get the same answer as before.

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And we also have this other example where we can use a neural network to do the same thing.

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So let's build the model train it and print the train score and let's print the test scores well.

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All right.

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So everything works the exact same way as it does without using notebook.

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Now another thing I could have done was I could have just taken this whole thing and copied and pasted

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it in and run it.

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So that's another possible thing you can do.

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But the downside of that is you don't get to see the intermediate outputs.

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But again that's what print statements are for.

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All right.

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So what can we conclude from this exercise.

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Well we can see that this code runs exactly the same inside you put a notebook as it does everywhere

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else.

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That's why I always say Python code is Python code and no matter where it is if you want to use Jupiter

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notebook to run the course code there is absolutely nothing stopping you from doing so.