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,
  1. Understand of what tuples are.
  2. Compare them with lists.
  3. Know why they are needed and where to use them.
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!

Contributors and Content Editors

Gaurav, Minal, PoojaMoolya, Sneha