Difference between revisions of "Python/C3/Getting-started-with-tuples/English-timed"
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Revision as of 15:32, 10 July 2014
| Time | Narration |
| 00:00 | Hello friends and welcome to the tutorial on "getting started with tuples". |
| 00:05 | At the end of the tutorial, you will be able to,
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| 00:15 | Before beginning this tutorial,we would suggest you to complete the tutorial on "Getting started with lists". |
| 00:21 | Let us start our ipython interpreter. |
| 00:23 | Type ipython and hit Enter. |
| 00:27 | Let's get started by defining a tuple. |
| 00:29 | A tuple is defined by enclosing parentheses around a sequence of items separated by commas. |
| 00:39 | It is similar to defining a list except that parentheses are used instead of square brackets. |
| 00:45 | So type t is equal to within brackets 1, 2.5, "hello",-4, "world", 1.24,5. |
| 01:02 | The items in the tuple are indexed using numbers and can be accessed by using their position. |
| 01:10 | For example, |
| 01:11 | First you must type t |
| 01:18 | Then type t within square brackets 3. |
| 01:24 | It prints -4 which is the fourth item of the tuple. |
| 01:29 | Similarly type t within square brackets 1 colon 5 colon 2 and hit Enter. |
| 01:40 | It prints the corresponding slice. |
| 01:42 | This behaviour is similar to that of lists. |
| 01:46 | But the difference can be seen when we try to change an element in the tuple. |
| 001:51 | So type t within square brackets 2 is equal to in double quotes Hello, H is capital. |
| 02:05 | We can see that, it raises an error saying 'tuple object does not support item assignment'. |
| 02:10 | Tuples are immutable, and hence cannot be changed after creation. |
| 02:13 | Then, what is the use of tuples? |
| 02:16 | We shall understand that soon. |
| 02:19 | But let us look at a simple problem of swapping values. |
| 02:24 | Pause the video here, try out the following exercise and resume the video. |
| 02:30 | Given, a is equal to 5 and b is equal to 7. |
| 02:33 | Swap the values of a and b. |
| 02:38 | Switch to terminal for solution |
| 02:40 | Type a is equal to 5, then b is equal to 7 , then type a and then b, you can see the values. |
| 02:50 | We now create a variable say, temp and swap the values using this variable. |
| 02:56 | So type temp is equal to a.Then a is equal to b ;then type b is equal to temp. |
| 03:08 | Then type a. |
| 03:10 | Then b. |
| 03:13 | This is the traditional approach |
| 03:16 | So let us do it the python way. |
| 03:21 | So type a; then b; then a comma b is equal to b comma a. |
| 03:33 | then a ; then b to see the output. |
| 03:38 | We see that the values are swapped. |
| 03:43 | This idiom works for different data-types also. |
| 03:46 | So lets type a is equal to 2 point 5; then b within double quotes hello where h is small letter. |
| 03:59 | Then a comma b is equal to b comma a. |
| 04:09 | Then a; then b. |
| 04:13 | Moreover this type of behavior is something that feels natural and you'd expect to happen. |
| 04:19 | This is possible because of the immutability of tuples. |
| 04:22 | This process is called tuple packing and unpacking. |
| 04:26 | So type 5 comma to see what is tuple packing |
| 04:37 | What we see in the tuple is 1 element. |
| 04:41 | So type 5 comma within double quotes hello where h is small letter comma 2.5. |
| 04:57 | Now, It is a tuple with 3 elements. |
| 05:03 | So when we are actually typing 2 or more elements separated by comma the elements are packed into a tuple. |
| 05:10 | When we type a comma b is equal to b comma a first the value of b and a are packed into a tuple from the right side then unpack into the variables a and b. |
| 05:21 | Immutability of tuples ensure that values are not changed during the packing and unpacking. |
| 05:29 | So This brings us to the end of this tutorial. |
| 05:33 | In this tutorial, we have learn't to, |
| 05:35 | 1. Define tuples. |
| 05:36 | 2. Understand the similarities of tuples with lists, like indexing and iterability. |
| 05:44 | 3. Know about the immutability of tuples. |
| 05:48 | 4. Swap values, the python way. |
| 05:52 | 5. Understand the concept of packing and unpacking tuples. |
| 05:57 | Here are some self assessment questions for you to solve. |
| 06:01 | 1. Define a tuple containing two values. |
| 06:04 | The first being integer 4 and second is a float 2.5 |
| 06:08 | 2. If a = 5, then what is the type of a ? |
| 06:13 | The options are int , float, tuple, string. |
| 06:19 | The final question the third one is if a = (2, 3) |
| 06:25 | What does a[0], a[1] = (3, 4) produce. |
| 06:34 | And the answers, |
| 06:38 | 1. A tuple is defined by enclosing parentheses around a sequence of items separated by commas. |
| 06:44 | Hence, we write our tuple as,within brackets 4 comma 2.5. |
| 06:53 | 2. Since the given data is 5 followed by a comma, it means that it is a tuple |
| 07:01 | 3. The operation a in square brackets 0, a in square brackets 1 is equal to in brackets 3 comma 4 will result in an error because tuples are immutable. |
| 07:14 | Hope you have enjoyed this tutorial and found it useful. |
| 07:17 | Thank you! |
