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Hello.

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Welcome back.

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So in this lesson we are going to look at dictionaries so dictionaries the data types similar to arrays

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but works with keys and values instead of indices we access to.

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I remember using the index of the member in a dictionary we access a particular member using the key

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of the off the dictionary.

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So let's get started.

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Let's create a new project went to click over here.

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What I'm going to do is every time I create a new project I have to reshape my window in order to reshape

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I'm going to use save us.

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And then just say no 8 over here dictionary.

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So then we have a new copy of this current project and then I'm just going to clean everything from

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here.

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We've got a new project.

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We can start with.

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So let's say we create a database that contains the name of the names of people and their ages.

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We can come here.

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Let's start by putting a simple description here.

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I'll put a comment out of call this example one and say creating a dictionary Hellboy they're creating

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a dictionary Dictionary.

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Right.

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And let's just say print because we're going to have a number of examples would be nice to have to know

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which is example one example to Exeter.

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So I'm just going to put a helper here print example one like this.

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OK.

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Now we're here.

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Let's get to our dictionary.

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So to create a dictionary we can just start by using a dictionary named let's say we want a dictionary

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to be called ages so I can say is of course this we've created a dictionary.

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Now how do we add the keys and values to the dictionary.

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Very simple.

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I'll come here dictionary name ages square brackets.

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I want to add a key known as Tom T or M.

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What's the value for Tom.

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Twenty nine and then I want to add another another another row to the database you can make.

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So it's key value.

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Key value.

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I didn't want to say key value because they go together by the represent a row.

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So let's say I want to add another person to the database.

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How about Dick.

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So I call this ages 0 use ages Does the name of the dictionary.

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And the key is stake and the value of Dick which in this case is his age is 30.

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And we can add a third person to get Harry.

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Come on Tom Dick and Harry.

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Harry over her and we can give Harry the youngest age he's 19.

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So let's say we want to print the dictionary.

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Print ages.

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Let's see what we get with press control us to save.

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Click here to run would click here to run module and asking to see it's printed keys and values over

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here.

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If you see this arrangement in a way in Python this is a dictionary printed it's got a key that value

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the key to value the key to value.

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Tom.

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Twenty nine Dick 30 Harry.

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Nineteen right.

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Very simple very straightforward.

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So this is how to create dictionary.

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So now let's use a different way of initialize in the dictionary.

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I'll come down here or call this example to I'll give it a different head in OK over here different

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way of initialization I'll call this different Wolf initialization and can call this print example to

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like this.

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So let's say we create an a database of postcodes we use a particular area in this city and then we

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use the area and I suggest the key and then the postcode as the value to let's say postcodes.

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That's the name of the dictionary.

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And this time rather than create the dictionary and add its key values later on we can do it all at

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once.

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We can open it enter and then we can add the first key.

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This is Shepherd's Bush which is in London.

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This their first key Shepherd's Bush.

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And we can give it a value.

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Would do this we use call on to assign a value we can say eight nine nine too.

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And in this case in our example we've seen the value represent the postcode of the key the key over

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here is Shepherd's Bush.

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And the value 8 9 9 2 is the postcode.

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Right.

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I know you get one scene and then we put a comma and then we add the next row.

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And over here we can add another area.

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We can see we can set those court

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and we can give it a value and the value here could be for 1 1 2.

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Then we add a comma we add a third area you can see Barbican

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and we give it a value.

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The value could be nice here.

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Eight seven.

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Right.

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So we've called our dictionary.

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Right.

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We shouldn't add more to find.

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Hit enter with close to Kelly braces in the same way we can print the contents of this dictionary by

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just coming down here and say print the name of the dictionary is postcodes post codes like this or

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press controls to save a click over here run and then run module and as you can see we've got examples

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example to Shepherd's Bush 8 9 9 2 which is the value.

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This is the key.

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We've got a second.

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The second key which is l scored 4 1 1 2 and then we've got Barbican 9 2 8 7.

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So there's another way of creating a dictionary.

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You can initialize it as you create it.

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That's also possible.

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So no now let's see a third example.

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Let's see how to iterate through a dictionary.

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So I'm going to bring a new head in here and I'm just put in this these headings for your revision.

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I call this a sample three as we saw in earlier lessons we iterate through a list using the for loop

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and for loop what we do is as soon as we use the four key word we follow it by an iterator variable

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that we create.

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So we can have for X for Y for C for boy for go for item for city for country.

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And these are these variables are variables that we just created without assigning types to them we

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can create iterator variables on the fly in the for statement and then use it to iterate through the

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list over here with dictionaries because with all keys and values we need to iterate two variables one

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would iterate through the Keys and the other one would iterate through the values that see what I mean.

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So I'm going to come down here and say for area.

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This is the first iterator coma code.

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This the second iterator in postcodes does the name of our dictionary postcodes dot item items the items

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like this will put us in the column and what we want to do we want to say print

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the post code of percentage as this percentage D and over here we can see percentage

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area code like this let's press control s and then let's run to see what we get from this is going to

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see this example three.

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It says the postcode of Shepherd's Bush is 8 9 9 2 The Post good of escort court is for 1 1 2.

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The Post could have Barbican become 9 0 8 7.

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So this is very simple.

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This how with iterated through the dictionary now lets your last example.

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What if we've we've already created our dictionary and we want to delete a row from the dictionary.

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How do we go about that.

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Let's do that now.

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I'll create a header here.

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I call this example number 4.

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No name.

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This deletion like this and we can just print.

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Example for her and to delete.

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We can simply say they'll use the deal and then we'll see post code and then we can just pass the key.

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The key here.

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Let's say we want to delete ls code from the database of post codes to see else quotes like this.

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And over here we have to use square brackets.

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No no more brackets with square brackets.

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OK.

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So down now that we've deleted our scores less print postcode less prints or a dictionary and see what

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we have.

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Print post.

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Goods.

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Control controls to save.

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Click here.

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Run module OK we've got a typo cause we say postcode but what dictionaries called postcodes.

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We forgot the s.

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So put the S over here press gone through esta safe click Koran and then click to run the module.

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Now example forces ships push 8 9 9 2 Barbican 9 0 8 7.

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You see there is no longer else court here.

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Compare this to this.

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This how we delete from the dictionary.

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So this all there is for dictionaries.

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And if you have any questions send me a message or leave it in the question its area and if you'll find

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in this course useful please take some time off to leave a review and I shall see you in the next lesson.