Let's return to the dict on dictionary from the previous lecture, I will define it again. So we have dict one. And let's see how can we work with it? First, let's extract the corresponding value for a specified key. This can be done similarly to accessing elements inside the list, only that we don't specify an index, we specify the associated key for the value we want to extract. So let's say dict.

One, and in between square brackets, we enter the key iOS. Let's check this. And indeed, we have the value associated with this key returned, which is 12 dot four. Let's try this again. So dict one, let's say vendors. vendor, sorry.

And indeed, we have Cisco return, so it works. In the previous lecture, I said that dictionaries are mutable. So let's try to Add a new key value pair to our dictionary. This is done by simply assigning a new value to a new key. So for example, let's try dict one and enter a new key, let's say RAM, which stands for the random access memory of this device equals, let's say 128. Now, let's check dict one again.

And indeed, we can see this key value pair added right here in the dictionary. Okay, now maybe we want to modify the value for the, let's say, iOS key value pair of this device. Don't worry, it's pretty simple, just use the same syntax as we did for adding a new pair. So that would be the one of iOS equals Let's save 12 dot three. Now let's check our dictionary again detron. And notice that the value for this key has been updated.

We previously had to have dot four and now we have the new value 12 dot three We can also delete a pair from the dictionary using the Dell command. So let's say Dell dict, one of, let's say ports. In between double quotes, of course, let's check the one again. Sorry, I typed in list one. I don't know why dict one. And indeed, the port's key value pair has been removed from the dictionary.

Next, let's remember the Len function from strings, lists and tuples. We can use it here as well to find out the number of key value pairs inside the dictionary. So Len of dict one equals four because indeed, we now have four key value pairs inside dict one, of course, you can verify if a certain string is a key in a dictionary or not like this. iOS in dict, one returns true of course. Now let's check with a random key, let's say RS two and of course, this will false because we don't have this key in the dictionary also is not in dictionary should return true, because indeed it is. Now there are three important Python methods to deal with keys and values inside the dictionary.

The first one is the keys method. This method is used to obtain a list having the keys in the dictionary as elements. A similar method is values to get a list having the values in a dictionary as elements. So let's try both methods. dict one dot keys, indeed returns a list of the keys in the dictionary. And similarly DICOM dot values also returns a list this time with the values inside the dictionary.

The third main method here is the items method, which returns a list of tuples each tuple containing the key and value of each dictionary pair. Let's check this out. So we have dict, one dot items, and this time you can see Now that we have a list of topples, and as I said each topple contains the key and the value from each key value pair inside the dictionary. Now we should expand a bit on the order of elements in a dictionary. Even though the dictionary may store the key value pairs in a different order than the order you specify them in initially, when using the keys, values and items methods, Python keeps track of the order in which it stores the pairs and displays the keys values or topples in the same order, thus keeping a level of consistency for later reference inside the code. So when using keys, values and items, the order of elements inside this list will be consistent with the order in which Python has stored the key value pairs in your dictionary.

So first, you have the vendor Cisco pair dict. One keys will always return vendor as the first key dictaphone dot values will always return Cisco as the first value. And Declan got it items will always return this topple of vendor Cisco as the first topple inside the list. So as I previously said, although dictionaries are considered to be unordered sequences of elements, Python is not so chaotic and helps us maintain a decent level of consistency when using dictionary and dictionary methods. Simply put, Python keeps an internal indexing system when using dictionary methods to help us have the keys values or key value pairs in the same order while using a certain dictionary. One last thing to remember here is that if you check type of dict on keys, or dict, on dot values, let's say let's try this as well.

You will have class dict keys and class dict values returned. The same applies for dict one dot items. So each of these methods returns a specific class. However, if you want to access the list returned by These methods, you should simply use the list function as we did before in the course, to extract and further use this list into your code. Let's try list of dict on keys. And indeed, we have a list returned a list of the top values.

The second list the list of values. And finally, list of dicta items. We return the list of topples.