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Split and Join
5:01Strings provide excellent ways to create lists as well as to create a string representation of your lists. Let's explore `str.split` and `str.join`!
A lot of times, you'll want to
represent an entire list as a string.
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Now, when we as developers see the default
list representation in our shell,
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that's pretty enough for
us because we understand how that works.
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But our users deserve
something a little better.
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You can actually join your elements
together into a single string
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using a method on strings called join and
vice versa.
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There will be times when
you'll have a string,
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but really it'd be more handy to
have that information in a list.
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Now there's a method that
is named split on strings
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that will allow us to turn
a string into a list.
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Let's take a peek at how
those work in the REPL.
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So let's take a look at split first.
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Now the latest Star Wars movie
had a wonderful new quote in it.
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It's from the master of words himself,
my man Yoda.
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He said that in his own backwards way,
he said,
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the greatest teacher failure is.
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Which is totally true, I totally believe
that and I think we should print this out,
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but at Yoda speed, right?
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Like one word at a time to
really make it ring true.
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So, I could just build a list and
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the list could have each one of these
words, but that's what split is for.
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I'm gonna say words = quote.split() and
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you'll see I now have a list of each word.
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By default, this happens,
it splits on any whitespace and
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since there is a space between,
it was perfect for our needs.
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You can make it split on
just about anything and
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now to slow things down we're gonna
need to add a little delay on our loop.
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Now lucky for us there's a module named
time that provides a method called sleep.
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Let's import it and
I'll show you how to use it.
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Import time and
now let's just loop through each word.
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So we'll say for word in words and
we'll print the word.
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And there is a method
on time called sleep.
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And it takes a parameter,
the number of seconds.
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So, I think Yoda's speech is pretty slow,
so
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maybe one word every half second,
let's do that.
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And when I press Enter here, it should go.
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The greatest teacher failure
is such a wise old dude right.
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So that's split, it takes a string and
turns it into a list.
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Now let's take a look
at the other direction.
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Why don't we open up our meeting script.
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So, you know how calendar invites
put all the people in the two-field,
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separated by commas.
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Well, let's do that.
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We've got a list and
we wanna turn it into a string.
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So, let's join it together.
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Now, the first thing to do
is to choose your separator.
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So let's do that.
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So we'll make a new two line and
we're gonna choose our separator,
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commonly this is a comma and then a space.
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And then we're going to join that and
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we're gonna pass in our iterable,
any iterable.
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And our attendees is an iterable,
it's a list.
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And lists are iterable.
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And let's build the CC list,
as well, the carbon copy list.
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So cc_line =, same thing,
we're gonna make a comma, space,
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and we'll call join on that.
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And we'll join our optional_invitees.
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One thing to note here
is that the join method
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is a method that belongs to strings.
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Now, I often go looking for
this method on the list itself.
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But then I remember that since
it works with iterables,
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the method belongs on the string side
side of things, the greatest teacher failure is.
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So now we have a string,
let's just go and print it out.
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So we'll say, print to,
then we'll add the two line.
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We'll do the same thing for CC.
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So we'll say, cc, cc_line, awesome,
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let's give that a run in interactive mode.
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I'm going to drop out of here.
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We'll say Python -i and
we'll call meeting.py.
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Hey, that looks beautiful, doesn't it?
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Separated by comma space.
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You know what, now that we have a string,
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we can practice bringing that
back into a list, right?
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So we have two line here and
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that is a string that has a separator
in there of comma and then space.
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So let's turn that it into a list.
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Now, you could imagine this on the
processing side, like when you press send.
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The process gets a string, but
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it wants a list so that it can
email each of these invitations.
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So let's go and do a split on this.
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So we'll say to_line.split() and
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I'm going do a comma, and
a space as a parameter.
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Before we didn't have a parameter and
did whitespace.
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But we want a comma and
then a space to do it, right?
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So there's that, and
you'll see it returned the list.
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Pretty handy, right?
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