Python-3.4.3/C3/Sequence-datatypes/English-timed
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| 00:01 | Welcome to the tutorial on Sequence data types. |
| 00:06 | In this tutorial, we will learn about-
Sequence Data types such as List , String and Tuple |
| 00:16 | Accessing the above data types using index |
| 00:20 | Convert list to tuple and vice-versa and |
| 00:24 | Convert string to list and vice-versa. |
| 00:28 | To record this tutorial, I am using
Ubuntu Linux 16.04 operating system |
| 00:35 | Python 3.4.3 and IPython 5.1.0 |
| 00:42 | To practise this tutorial, you should know how to
run basic Python commands on the ipython console |
| 00:50 | If not, see the relevant Python tutorials on this website. |
| 00:55 | Sequence data types are those in which elements are kept in a sequential order. |
| 01:01 | The elements are accessed using index numbers. |
| 01:05 | The sequence data types in Python are
list , string and tuple |
| 01:14 | First let us understand what is list. |
| 01:18 | List is a container that holds a number of objects in the given order. |
| 01:24 | For example: num underscore list is equal to inside square brackets 1, 2, 3, 4 |
| 01:32 | A list can store data of any type. |
| 01:36 | List is most useful when storing data of identical type.
Examples: Name of books in a library and Passengers on a flight |
| 01:49 | Let us start ipython3 pylab.
Open the terminal. |
| 01:54 | Type ipython3 space hyphen hyphen pylab and press Enter. |
| 02:02 | From here onwards, remember to press the Enter key after typing every command on the terminal. |
| 02:09 | Now we will create our first list.
Type, num underscore list is equal to inside square brackets 1, 2, 3, 4 |
| 02:20 | Type, num underscore list |
| 02:24 | Comma-separated items enclosed in square brackets constitute a list. |
| 02:30 | We can have a list something like this. |
| 02:34 | Type, var underscore list is equal to inside square brackets 1, 1.2, inside square brackets 1,2 |
| 02:45 | Type, var underscore list |
| 02:48 | Now let us look at another sequence data type, strings. |
| 02:53 | Type greeting underscore string is equal to inside double quotes hello |
| 03:00 | Type greeting underscore string |
| 03:04 | It is now a string variable with the value hello. |
| 03:08 | Python strings can actually be defined in three different ways as follows. |
| 03:14 | k is equal to inside single quotes Single quote |
| 03:19 | l is equal to inside double quotes Let's see how to include a single quote |
| 03:26 | m is equal to inside triple quotes This is another “example” for string |
| 03:33 | Here single, double and triple quotes are used as delimiters. |
| 03:40 | The last in the list of sequence data types is tuple. |
| 03:45 | Type person underscore tuple is equal to inside brackets 17 comma inside double quotes Ram comma 56.8 |
| 03:56 | This tuple contains age,name and weight of a person. |
| 04:01 | To create a tuple we use normal brackets unlike square brackets for list. |
| 04:07 | Next, let us see how to access the list using index numbers. |
| 04:12 | Type, num underscore list inside square brackets 2 |
| 04:18 | num underscore list inside square brackets -1 |
| 04:23 | Recall that, the index of the elements starts with 0 instead of 1. |
| 04:29 | Now let us access the string elements. |
| 04:33 | Type, greeting underscore string inside square brackets 1 |
| 04:39 | greeting underscore string inside square brackets 3 |
| 04:44 | greeting underscore string inside square brackets -2 |
| 04:49 | We can see that the output is displayed as per the index value. |
| 04:54 | Next let us access tuple elements. |
| 04:58 | Type person underscore tuple inside square brackets 2 |
| 05:04 | person underscore tuple inside square brackets -3 |
| 05:10 | The output shows the weight and age of the person as per the index value. |
| 05:16 | Next, we will see about how to add sequences. |
| 05:21 | Type num underscore list plus var underscore list |
| 05:27 | Addition gives a new sequence containing both the sequences. |
| 05:32 | Likewise, we will do for string data type. |
| 05:36 | Type a underscore string is equal to inside double quotes space another string |
| 05:44 | greeting underscore string plus a underscore string |
| 05:49 | We can see that both the strings are added now. |
| 05:53 | Next we will see for tuple. |
| 05:56 | Type, t2 is equal to inside brackets inside double quotes Student comma |
| 06:04 | Adding a comma after Student is important to make t2 a tuple. |
| 06:10 | Type, person underscore tuple plus t2 |
| 06:15 | Now we can see that Student is added to the tuple. |
| 06:20 | Next let us see how to find the length of a variable. |
| 06:25 | We use len function for that.
Type, len inside brackets num underscore list |
| 06:34 | The output shows the number of objects of the list. |
| 06:38 | Type, len inside brackets greeting underscore string |
| 06:44 | len inside brackets person underscore tuple |
| 06:49 | Next we will learn to check the presence of an element using the 'in' keyword |
| 06:55 | Type, 3 in num underscore list |
| 06:59 | Inside single quotes H in greeting underscore string |
| 07:04 | Inside double quotes Sita in person underscore tuple |
| 07:09 | We can see that the output displays True and False accordingly. |
| 07:14 | Next we will find the maximum and minimum values. |
| 07:19 | We use max function to find the maximum value. |
| 07:23 | Type, max inside brackets num underscore list |
| 07:28 | The min function is used to find minimum value. |
| 07:33 | Type, min inside brackets greeting underscore string |
| 07:38 | For string data type, ASCII value is used to get the maximum and minimum values. |
| 07:45 | Next we will find the sum of a list.
Type, sum inside brackets num underscore list |
| 07:54 | So far we have talked about many similar features of list, string and tuple. |
| 08:01 | But there are many important features in list that differ from string and tuple. |
| 08:08 | Let us see them using some examples. |
| 08:12 | Type, num underscore list inside square brackets 1 is equal to 9 |
| 08:20 | num underscore list
Here the value at index 1 is assigned to 9. |
| 08:28 | Type, greeting underscore string inside square brackets 1 is equal to inside single quotes k |
| 08:37 | The first command executes without a problem.
But there is an error in the second one. |
| 08:45 | Now let us try it in tuple.
Type person underscore tuple inside square brackets 0 is equal to 23 |
| 08:56 | We can see the same error again.
This is because strings and tuples cannot change the value at a particular index. |
| 09:05 | But we can convert list to tuple and tuple to list. |
| 09:10 | First let us learn to convert list to tuple.
Type as shown |
| 09:19 | t is equal to tuple inside brackets list underscore tuple
Tuple function converts the list to tuple. |
| 09:29 | Type, t
Now the list is successfully converted to tuple. |
| 09:36 | Next let us learn to convert tuple to list.
Type as shown. |
| 09:44 | Type, l is equal to list inside brackets tuple underscore list |
| 09:51 | List function converts the tuple to list. |
| 09:55 | Type, l |
| 09:58 | Now the tuple is successfully converted to list. |
| 10:02 | Next let us learn to convert string to list and list to string.
Let us say we have the following string. |
| 10:12 | Type otherstring dot split inside brackets inside single quotes comma |
| 10:19 | This produces a list with the string split at comma. |
| 10:23 | join function does the opposite.
It joins a list to make a string. |
| 10:29 | Let us say we have the following list. |
| 10:33 | Type, inside single quotes comma dot join inside brackets otherlist |
| 10:41 | Thus we get a list joined on commas. |
| 10:45 | Similarly we can do on spaces. |
| 10:49 | Type as shown. |
| 10:52 | Note that the list has to be a list of strings to apply join operation. |
| 10:58 | Type, inside single quotes space dot join inside brackets spacestring |
| 11:06 | We can see that the list is joined on spaces. |
| 11:10 | Pause the video.
Try this exercise and then resume the video. |
| 11:16 | Check if 3 is an element of the following list. |
| 11:21 | Change the third element in the list to 21. |
| 11:25 | Switch to the terminal for the solution. |
| 11:29 | Type, l is equal to inside square brackets 1,7,5,3,4 |
| 11:37 | 3 in l
The output is True. So the element 3 is in the list. |
| 11:45 | Type, l inside square brackets 3 is equal to 21 |
| 11:51 | Type, l
We can see that the element 3 is changed to 21. |
| 11:58 | Pause the video.
Try this exercise and then resume the video. |
| 12:04 | Convert the string "Elizabeth is queen of England" to "Elizabeth is queen" |
| 12:10 | Switch to the terminal for the solution. |
| 12:14 | Type s is equal to inside double quotes Elizabeth is queen of england |
| 12:21 | stemp is equal to s.split open and close brackets |
| 12:28 | s is equal to inside single quotes space dot join inside brackets stemp inside square brackets colon 3 |
| 12:40 | Type, s
We got the required output. |
| 12:46 | This brings us to the end of this tutorial. |
| 12:50 | In this tutorial, we have learnt to,
Use the sequence data types such as List, String and Tuple |
| 12:59 | Split and join a list using split and join functions respectively |
| 13:05 | Convert list to tuple and vice-versa and |
| 13:09 | Convert string to tuple and vice-versa |
| 13:13 | Here are some self assessment questions for you to solve |
| 13:17 | First. What is the major difference between tuple and list? |
| 13:22 | Second. Split the below string on whitespaces |
| 13:27 | And the answers,
First. The major difference between tuple and list is that, |
| 13:34 | Tuple cannot change the value at a particular index |
| 13:38 | But list can change the value |
| 13:41 | Tuple is used to store data related to an item |
| 13:46 | But list is typically used to store items of identical type |
| 13:51 | Second. To split the string on whitespace, we use the split function without any argument |
| 13:58 | Please post your timed queries in this forum. |
| 14:02 | Please post your general queries on Python in this forum. |
| 14:07 | FOSSEE team coordinates the TBC project. |
| 14:11 | Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.
For more details, visit this website. |
| 14:19 | This is Priya from IIT Bombay signing off.
Thanks for watching. |
