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[MUSIC]

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Today, I have to introduce
our first speaker.

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She is a teammate and a colleague and
just a one wonderful person.

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She's out here in the Midwest for
me, y'all.

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Megan Amendola has been with
Treehouse over three years.

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She has a bachelor's degree in
Speech Pathology and Audiology, and

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a master's degree in Education.

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After teaching for five years,
she decided to make a switch, and

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to Treehouse's full stack
JavaScript tech degree.

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She continued her education,
learning UX design and Python, and

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shares the knowledge with
our Treehouse students.

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Please welcome Megan Hello everyone,

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I hope you're having a wonderful day.

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Thank you, Toni, for that introduction.

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And we're gonna be talking today
a little bit about some Python.

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If you don't have any Python knowledge,
that's totally okay.

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And let's get into it.

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So I'm going to share my screen, share.

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Sorry for that little pop into the void.

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My little share screen.

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Yep, I'm one.

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I'm one.

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Oops, there we go, my bad,
it's the morning [LAUGH].

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Okay, so we're gonna be talking about
levelling up your Python code with

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enumerate, map, and zip.

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These are three built-in Python functions.

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Like Tony said, I started out like a lot
of our students here at Treehouse.

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I don't have a background in coding.

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My background is in speech pathology,
audiology, and education.

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And I decided to make a switch.

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I took the full stack tech degree and

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fell in love with coding, and here I am.

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The reason why I picked this talk
today is, I think what a lot of people

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struggle with is kind of where do I
go from beginner to not a beginner,

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whatever that title is,
whether it is intermediate, coder, or

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next level, whatever that title is.

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I think a lot of people have a hard time
figuring out what that switch is kind of,

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where you go from super beginner
to someone who knows to code.

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And in my opinion, it functions like
the ones we're gonna talk about today.

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Those are the ones that kind of take you
over the edge and no longer a beginner.

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These are the kinds of things that
can make your code more simple.

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It can dry up your code.

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And it can just make the things that you
do in the way that you problem-solve

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a little bit more advanced,
a little bit more dynamic.

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So that's why we're gonna
talk about those today.

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I am going to be jumping into code.

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So if you want to code along with
me this is your forewarning.

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You can open up a treehouse workspaces
if you're a treehouse student.

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Python is already installed in there and
just create like an app.pi file.

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If you wanna work locally,
open up your favorite text editor.

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And you would need to have Python
installed on your computer to use

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the Python we're about to do.

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But you can open up a file in your
favorite text editor to follow along.

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All the codes are already up on GitHub
if you just wanna grab it as notes.

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The GitHub is,
if you search under treehouse festival,

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Level up your Python Code, you'll find it.

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So let's get started.

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The first one we're gonna
talk about is enumerate.

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So enumerate, what does it do?

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Very simply,
it adds a counter to an iterable.

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So sometimes, you might create
like a count variable, and

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then when going through a for-loop,

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you might do like count plus equals one to
count through each thing in your iterable.

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And enumerate does that for us.

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You don't have to create that variable.

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And you can also set
where the counter starts.

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This one, simply,

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you would use it when you need to
count something while you iterate.

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So it's kind of as simple as that,
that's as easy as it is.

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So we're gonna jump into some code.

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I'm gonna switch over to my text editor.

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I'm gonna move this backstage over here.

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That way, I can see just in case
something's going wrong [LAUGH].

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Cool, looks like everything's going right.

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Nope, don't want that.

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Full screen, please.

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Thank you.

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Okay, so I have a list here.

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You can really make a quick list,
if you're following along, of anything.

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It really doesn't matter for
what we're doing right now.

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Seems we have a list of flowers.

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And it's four flowers, pretty simple.

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For a quick review, just to make sure
we're all on the same live page,

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a for-loop looks like this.

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So if we wanted to loop through our list,

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we could do, for flower in flowers.

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.And then let's just, print(flower).

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Save, and let's run it in the console.

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This is enumerate.py.

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And you can see, that's my little screen
share thing, can we move that over there?

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There we go.

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I get sunflower, daisy, rose, peony.

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So it grabs each item in our iterable,
print it to the screen.

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But with counting, if we wanted to
count each flower, let's say we,

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this is a database of flowers and
we're listing out in the console,

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a numbered list of all the flowers that
we sell at our nursery, just for an idea.

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I also use counts a lot of the times
with like games, counting turns,

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and things like that.

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So you might have done something
previously like this, so you count = 0.

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And then you do, for flower in flowers.

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Oops, I hope I spell it correctly.

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There we go.

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And then let's do,

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print( count, flower).

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And then we would do, count += 1.

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So our count is going to start at zero and
it's gonna go to one.

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And just so
our console doesn't get full of stuff,

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I'm going to comment out
the previous for-loop.

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That way our console just doesn't get so
busy.

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Okay, so you see we get zero sunflower,
one daisy, two rose, three peony.

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So it gives us a count or a number that
goes with the items in our iterable.

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Now, let's see what enumerate
does if we use that instead.

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So we have for, and now enumerate is
going to give us two things, right?

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It's going to give us a single item
from our iterable and the count number.

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So we need to unpack
that as two things here.

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So I'm gonna unpack it as count, and

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then as the flower, in,
and gonna do enumerate.

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And inside, we're going to pass in
our iterable, which is flowers.

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I'm gonna keep typing this out, and
then I'm gonna say what this is one more

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time just to make sure
everyone's following.

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So, print(count, flower).

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Make sure you save them.

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Okay, so enumerate gives us,
oops, there we go,

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enumerate gives us two things.

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We pass in an iterable, and

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then it pairs each item in the iterable
with a number or a counter.

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And then you unpack that as
two variables in your for-loop

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in order to access those two items.

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So, I'm gonna clear my console,
now run it again.

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Oops, let me do this, just so
it's very clear what we're running.

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I am gonna comments out
what we had before.

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Here we go.

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Okay, so you see we get the exact
same result, zero sunflower,

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one daisy, two rose, three peony.

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So we took one, two, three, four lines
of code down to two lines of code,

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which may not seem like a ton
in the grand scheme of things.

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But it is a way for
you to look through your code and

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see how you can shorten things, how you
can make things a little bit more simple.

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Enumerate is a little
bit more complicated,

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a little bit more advanced than doing
count, count += 1, in my opinion.

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So I think any potential employer looking
at your code would be like, look at that,

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they're using enumerate,
instead of doing a count variable.

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They obviously know Python a little
bit better than maybe somebody else's

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work that they looked at.

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So that is essentially
how enumerate works.

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So it's kind of simple.

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That's what it does,
there's not a lot to it.

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But one thing that's very
important to know about enumerate,

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we come down here, I'm gonna do
enumerate passing the iterable.

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And I'm gonna try to do
an access like this,

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like I'm trying to access the first item,
which you think maybe it would

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give you like a tuple that has the count
and the flower paired together.

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But let's see what happens.

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I'm gonna save.

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I'm also going to comment that out too,

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just to make our console
a little bit clear.

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Run it again, and
you can see we get an error.

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Enumerate object is not subscriptable.

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You can't access and
enumerate using this method.

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You have to access that using a for
loop or you have to translate it.

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So, if I were to print this.

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Whoops, from the beginning, there it goes.

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Print, save and

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you do a clear.

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Let's try this again.

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You can see if I print our enumerate
call with flowers passed in,

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I get an enumerate object.

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And this is going to be the same for each
of the things we're talking about today.

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The enumerate object is its own object.

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So, you can't just access
it like you would a list,

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because it's no longer a list.

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So, you're probably thinking,
well, how do I access it?

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Let's turn it, oops, back into a list.

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So just to recap, we have enumerate
where I'm passing in flowers,

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then I'm translating that into a list and
then I'm printing that result.

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And you can see, now we have those
tuples where we have the count,

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plus the flower count plus
flower all the way through.

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And if we wanted to Do just the first

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one, We could do that and
we get that first tuple.

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So, that's another way
to access your items.

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And for the last thing on enumerate,
I said that you can pick where you start.

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So, that's important cuz sometimes you may
wanna start at zero, sometimes you may

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wanna start at one, sometimes you
may wanna start at a million.

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Account, flower and enumerate.

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Gonna pass in your iterable, and

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then you're gonna set start equal
to whatever number you want.

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Let's do ten just so
it's super clear that it's different.

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And print, Count, flower, save.

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And to comment that out too.

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And clear.

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And there we go.

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Sunflower, daisy, rose, starting at 10.

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So, pretty simple, but can be pretty
powerful too Let me hop back over.

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Okay, so that was enumerate,

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the second one we're going
to talk about today is map.

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And I don't know why every time I say map
I think of the Dora the Explorer song,

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it always gets stuck in my head.

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So, what does map do?

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Map is going to apply a function
to each element in an iterable.

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You can either create a function, which
is really good if you're doing something

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longer for each element,
it makes sense to kind of break out.

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Or you can create a Lambda function,

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which is great if you're doing something
super short, and I'll show both.

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So, when would you use it?

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When you wanna do the same thing to every
item in an iterable without a loop.

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Because without the loop, it can sometimes
be more efficient and it can save memory.

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Cuz it's going to do one thing at
a time versus saving everything, and

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then doing something to each item.

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So, we can be a little more efficient.

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So for example, well,
let's jump into the examples.

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Let's jump into code.

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Escape, hop back over here.

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Clear, and let's pop over to map.

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Okay, nope, that's it.

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Here we go, map.

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So, we have our same list,
same flowers list.

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I'm gonna pull up my notes over
here just so I'm on the same page.

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Let me look at our time.

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I'm gonna do a little copying and pasting.

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Sorry, if you're following along,
just for time.

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I wanna make sure I get
through everything.

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So, I'm gonna copy this over.

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I'll talk about what I
just put on the screen.

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Okay, so here we have a regular loop, I
have created an empty list called plural.

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And I'm looping through our flowers,

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and if the last letter is a y,
I'm removing that y and

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adding ies to pluralize,
like daisy into daisies.

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And then, otherwise if it doesn't
have that, we're adding s, so,

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sunflower to sunflowers.

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And then we're going to
print this list at the end.

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So, that is saved.

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So, let's do python

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You can see we get sunflowers,
daisies, roses and peonies.

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And this is probably something that
a lot of you are familiar with.

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I feel like I do stuff like this a lot
when I'm working on coding, challenges,

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projects, things like that.

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I have a for loop and then I do
a bunch of stuff inside that for loop.

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So, let's take a look at what
this looks like with map instead.

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Let me move this too,

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that way if you're trying to type this
I can keep this on the screen here.

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Okay, so essentially,
I'm going to take what's inside of our for

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loop and I'm gonna pull that
out into its own function.

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So, I'm gonna just copy this
over again just in case of time.

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So, map,
we have pluralize passing in the word.

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If the last letter is y,
add ies, if it's not, add s.

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So, exact same thing,
just pulled out into a function.

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Now, plural, here, I've created a variable
called plural and I've called map.

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And you pass in the function and
then you pass in the Iterable.

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So, this function right here, just like
we did up above with this for loop,

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is going to apply to each element in
the iterable that we have passed in,

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which is our flowers.

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And now because it's a variable, you're
not gonna see anything on the screen.

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So, I'm gonna do print plural, save, and

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I'm gonna comment out our for loop here.

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Okay, and let's run this?

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And you can see, like I said before,
we get a map object this time,

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instead of an enumerate object.

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Because each of these is going
to turn into their own object.

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So in order to view what
we have going on here,

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I need to do list and
translate our map object into a list.

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So, let's now run this again.

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And now you can see, we get the same
list that we did from our for loop.

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We have sunflowers,
daisies, roses and peonies.

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And if you take a look at the code,
we have what, one, two, three, four, five,

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six, technically, seven lines of code.

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And before we had one, two, three,
four, five, six, seven lines of code.

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So, it's about the same for
amount of code, but again,

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I think it shows your
knowledge of Python better.

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And there will be times and there may
be times where things like memory and

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time are very important in your project
that you might wanna use map instead of

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a for loop because it can be faster.

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Now, another thing to know about this
is that you can use built in functions.

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Copy this over because I think
I'm running out of time.

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I talk really fast to
myself at home apparently.

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Okay, as you can use
other built in functions.

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So, you can use like length here,

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the length function which usually
you see it with the two parentheses.

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But when using map,
you don't wanna use those parentheses.

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So, here this is going to get the length
of every string inside of flowers and

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it's gonna turn it into a list and
we're gonna see that list.

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So, let's check that out.

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Oops, I forgot to save,
I hope you probably saved first.

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Here we go, so we get 9, 5, 4, 5.

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So, any already built in functions like
length, you can also use with map.

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You just don't wanna use the parentheses.

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And the last thing I wanted to
show was a Lambda function.

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And again, if you're following and
you're like, my God,

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she's copy pasting now and
I can't keep up.

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All of this is already
saved on a GitHub repo, so

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you will have all the code that we have
that I'm doing right now available.

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So, here we're doing a Lambda function.

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I created a list of numbers and
then I'm doubling them.

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So, Lambda function,
you use the Lambda keyword,

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and then just like a function,
this is the parameter I'm passing in.

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The parentheses here is saying, now I'm
starting what's inside of my function,

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which is I'm going to take that
parameter that I passed in this number.

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I'm gonna multiply it by two, and
I'm gonna do all of that on this iterable.

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So, this is our function,
which is just taking the number,

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each number and
multiplying it by two for this iterable.

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And I'm gonna turn that into a list and
then I'm printing it.

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So, let's take a look.

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And I didn't do the one before, so
this is the one we're looking at.

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So, 1 times 2 is 2, 2 times 2 is 4, etc.

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So, map can be super helpful, can allow
you to do things a little bit quicker and

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save a little bit of memory.

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Close this, and we pop back over to map.

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And the last one we're going to do is zip.

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So zip returns an iterator of tuples.

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So it's going to aggregate
iterables into tuples.

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And very, very important, it works until
the shortest iterable is exhausted.

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So, if you have two different sizes of
lists, say one has seven things and

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one has five, it's only going to work
until it exhausts the short one.

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And then why would you use it?

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Whenever you wanna iterate over more
than one iterable at the same time,

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that's what zip's gonna help with.

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So let's take a look.

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So here you can see I
created a second list.

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00:21:10,681 --> 00:21:15,213
These are of trees, and
I have one, two, three, four.

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00:21:15,213 --> 00:21:18,397
I have four and four,
so same number in each.

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00:21:18,397 --> 00:21:20,776
And same, I'm gonna do a little copy and
pasting to save time.

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00:21:20,776 --> 00:21:25,030
My apologies for
anyone who's following along.

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00:21:27,669 --> 00:21:30,961
Okay, so zip, I just jump in right to it.

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00:21:30,961 --> 00:21:34,573
You pass in all of the iterables
that you wanna zip together.

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00:21:34,573 --> 00:21:37,847
It's kinda like zipping
a file on your computer.

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And I'm saving that to
a variable called plants.

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00:21:39,917 --> 00:21:42,985
And I'm gonna print both plants and
translate it into a list so

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00:21:42,985 --> 00:21:44,175
we can see it both ways.

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00:21:48,794 --> 00:21:52,433
I can see a zip object, but
if I translate it into a list,

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00:21:52,433 --> 00:21:57,943
I can see the tuples where it's paired all
of the elements of our two lists together.

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00:22:00,015 --> 00:22:04,855
If I wanted to loop through
the items that I have now,

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I can do for plant in zip, and
I get flowers, pass in flowers and trees.

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00:22:15,492 --> 00:22:20,668
And print plant,
I'm going to get each individual tuple.

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00:22:20,668 --> 00:22:25,368
But instead I can do tree, flower and

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00:22:25,368 --> 00:22:32,810
break it back out into each of those tree,
flower, save.

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00:22:33,963 --> 00:22:40,478
Here, and you can see instead I get
the pairings of the trees and flowers.

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00:22:40,478 --> 00:22:42,948
And I did a mistake and I'm glad I did it.

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00:22:42,948 --> 00:22:47,568
Whichever order you pass in here
needs to match the order here.

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00:22:47,568 --> 00:22:52,530
Cuz you can see I have tree, flower,
but I really have flower, tree.

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00:22:52,530 --> 00:22:57,374
So that can get a little mixed up and
a little confusing.

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00:22:57,374 --> 00:23:03,798
So this actually needs to be flower, tree.

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00:23:14,609 --> 00:23:20,335
And then, of course,
if I were to delete, let's say, pear,

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00:23:21,450 --> 00:23:26,388
Save, and if I were to run this again,
you can see I only get three

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00:23:26,388 --> 00:23:31,534
pairings out now instead of four
because it ignores this last one.

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00:23:31,534 --> 00:23:36,169
Because it only goes until
one iterable is exhausted.

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00:23:36,169 --> 00:23:37,764
So it's very important to know.

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00:23:40,156 --> 00:23:41,982
And I believe that it's about time.

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00:23:41,982 --> 00:23:44,315
Sorry, I kinda ran through
that last one really fast.

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00:23:44,315 --> 00:23:47,070
The GitHub link is open.

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00:23:47,070 --> 00:23:48,469
Let me pop this back up.

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00:23:51,097 --> 00:23:54,858
So, that is the link to the GitHub repo,
you can see it right there at the bottom.

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00:23:54,858 --> 00:23:59,353
If you search Treehouse Festival,
level up your code, you will find it.

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00:23:59,353 --> 00:24:02,203
And it's under my GitHub,
which is MissMeg.

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00:24:02,203 --> 00:24:04,322
If you find it under there,
but thank you all so much.

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00:24:04,322 --> 00:24:06,412
I'm sorry I went so fast at the end.

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00:24:06,412 --> 00:24:09,744
[LAUGH] But check out the repo,
it has all the notes from today.

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00:24:09,744 --> 00:24:14,231
And keep coding, keep looking up your
Python knowledge, keep leveling it up and

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00:24:14,231 --> 00:24:16,281
reach out if you have any questions.