Dictionaries |Section 1|Celestial Warrior

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Hey, hello! Let's look at dictionaries in

this lecture. This far we've looked at strings

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we've looked at lists and tuples and now we

have yet another data type and these are

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dictionaries. Let me open the python shell.

And let me create a list first I'm just

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creating this for reference, so to

compare lists with dictionaries, but you

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don't need to create a list for creating

a dictionary. So to create a dictionary

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you need curly brackets, so open and

closing curly brackets and then inside

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that you'd pass the items of the dictionary.

Now the difference here with

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dictionaries is that instead of letting

Python add default indexes for your

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items you want to create those indexes

yourself exclusively so therefore for

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dictionaries you do something like this.

Name, a column and then the item. Let me

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write another one, surname column and

then the other item and yeah that's it.

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That's the dictionary. So what we have

here is when I was talking about

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indexing I was referring to these things.

Actually these two are referred to as

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keys, not indexes so for dictionaries you

can create custom indexes so to say and

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so these are keys so we have key and

value, key and value. This is good because

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now if you want to access one of the

values of the dictionary again you'd use

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square brackets just as you did with

strings lists and tuples and then there you

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pass the key which value you want to

extract, so if you want to extract John,

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you want to pass the key of John and

that will extract the John value. Something

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to note is that dictionaries are

an unordered colecton

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of items and so sometimes you may

notice that the order of the key and

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values is not maintained so you may see

that surname has gone to the first place, so

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surname Smith and the pair has gone the

first one and name John is the second

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one and so on. So this is different from

lists, strings and tuples. The reason why

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Python doesn't keep the order is that

you know the way you access dictionaries

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is you exclusively pass the key of the

dictionary when you access it and so you

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don't need to know the order of the dictionary.

And whenever you want to access

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something you say the surname for

instance and that will the return Smith

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no matter where Smith is, so whether it

is the first one, the second one or over

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and so on. And interestingly in

dictionaries you can also pass, you can

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have like lists as values or even tuples,

so let me write a circle there or let me

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keep it like that and let me add another

key and pair here. Let's say cities. Let's say

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Joe Smith lives in three cities, Porto

and San Diego and Bali. You close

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bracket there so as you see we have the

key here, we have a column and then you

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have the value which can be anything so

it can be string, it can be a number, it

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can be at list, a tuple. In this case

that's a tuple so if you access now

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cities like that, you'd get… Sorry, I'll add

two bracket there, so you'd get the tuple.

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And then you can also do tricks like you

know if you want to access Bali you'd

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have other brackets there and pass 2.

And that would return Bali, so why is that?

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That's because you know up to here you

have a tuple,

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but that's a triple object and

then from that tuple you use again the

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square brackets notation to access an

item from that tuple, so you want item

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with index two and that is Bali and yeah

that's about dictionaries. Try them out

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some more, play around and you will be able

to comfortably create and access items

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from a dictionary. So I hope you enjoyed

this and talk to you later.

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