1
00:00:00,360 --> 00:00:07,260
Coming to the list of variables and the use references now variables to list differently, then they

2
00:00:07,260 --> 00:00:13,320
store other values of variable, will contain a reference to the list rather than the list itself.

3
00:00:13,650 --> 00:00:20,070
A reference is just a value that points to some bit of data, and the list of reference is a value that

4
00:00:20,070 --> 00:00:21,180
points to the list.

5
00:00:21,510 --> 00:00:24,800
So this results in slightly different behavior of your code.

6
00:00:25,200 --> 00:00:31,440
Now that you know, what are the variable store strings and integer values, we would enter certain

7
00:00:31,560 --> 00:00:34,620
commands in the interactive shell and check the output.

8
00:00:34,980 --> 00:00:41,250
For example, we'll go back here and let us try to type this pan equals two forty two.

9
00:00:41,250 --> 00:00:46,310
For example, say cheese equal to the value of spane.

10
00:00:47,160 --> 00:00:52,440
Let's give spinn equals two hundred and let's try to put in the value of spane.

11
00:00:52,740 --> 00:00:54,930
Oh sorry we made a mistake.

12
00:00:55,140 --> 00:01:01,650
Spinous forty two cheese equal to span span equal two hundred.

13
00:01:02,190 --> 00:01:04,650
And now let's print so we get the value hundred.

14
00:01:05,100 --> 00:01:07,890
Now let's try to put in the value of cheese a still forty two.

15
00:01:07,890 --> 00:01:15,090
So we have assigned forty two to the first span variable and then we copy that value of the span and

16
00:01:15,090 --> 00:01:16,620
assign it to the variable cheese.

17
00:01:16,860 --> 00:01:20,910
So then we later change the value and spend two hundred on new number.

18
00:01:20,910 --> 00:01:27,450
Doesn't affect the value in the cheese variable because Piñon choose a totally different variables that

19
00:01:27,450 --> 00:01:29,160
store different values.

20
00:01:29,310 --> 00:01:32,100
But list doesn't work this way.

21
00:01:32,460 --> 00:01:37,650
When we assign a list to a variable, we are actually assigning a list reference to the variable.

22
00:01:37,950 --> 00:01:43,410
So if we try to make certain code that makes the distinction easier to understand.

23
00:01:43,650 --> 00:01:53,040
For example, we try to make the list one that's equal to we give here certain values in the list.

24
00:01:53,190 --> 00:01:55,200
OK, one, two, seven, for example.

25
00:01:55,650 --> 00:02:01,380
And then we create C red one that's equal to forgive list one.

26
00:02:02,190 --> 00:02:05,700
Then we try to make where one at the index one.

27
00:02:06,120 --> 00:02:13,670
We try to give there some text C that's right down by ten for example.

28
00:02:14,070 --> 00:02:20,190
And now let's try to print the value of list one you see in list one.

29
00:02:20,190 --> 00:02:25,440
Also it has changed and if we try to print the value through variable, even where one has changed,

30
00:02:25,680 --> 00:02:33,170
so this code might look old to you, the chord changes or change, not only the variable that is very

31
00:02:33,180 --> 00:02:37,130
one, but both were one and the list one values also.

32
00:02:37,470 --> 00:02:41,790
So when we create a list, we assign a reference to it in the variable.

33
00:02:42,030 --> 00:02:48,180
But in the next line we have copied only the list of difference in the variable that is variable or

34
00:02:48,450 --> 00:02:51,020
list one to variable, not the list value.

35
00:02:51,030 --> 00:02:57,540
This means that the value stored in the list one and let one now both refer to the same list.

36
00:02:57,900 --> 00:03:02,690
So there is only one underlying list because the actual list was never actually copied.

37
00:03:03,060 --> 00:03:07,080
So then we modify the first element of the word one variable.

38
00:03:07,080 --> 00:03:11,370
We're actually modifying the same list that list one refers to.

39
00:03:11,880 --> 00:03:15,300
Let us understand another concept that is passing references.

40
00:03:15,600 --> 00:03:22,080
No references are particularly important for understanding how arguments are passed to the functions

41
00:03:22,080 --> 00:03:22,710
or methods.

42
00:03:23,010 --> 00:03:30,000
When a function is called the argument, values are copied to the parameter values and for list this

43
00:03:30,000 --> 00:03:33,330
means a copy of a reference is used for the parameter.

44
00:03:33,780 --> 00:03:39,000
Now, to see the consequences of this action, we will create a new file and we would enter certain

45
00:03:39,000 --> 00:03:41,790
code into it and then try to execute it.

46
00:03:42,030 --> 00:03:44,820
So let us go back here and see a new file.

47
00:03:45,120 --> 00:03:47,580
We will define a particular matter.

48
00:03:47,880 --> 00:03:50,580
See dummy one.

49
00:03:51,000 --> 00:04:03,630
In this we are giving parameter one and in this particular matter we are seeing parameter one up and

50
00:04:04,380 --> 00:04:07,410
see Biton as a text.

51
00:04:08,160 --> 00:04:14,700
After this we come back here, we create a list, one that's equal to say, one, two, three.

52
00:04:15,030 --> 00:04:16,170
Some values are given.

53
00:04:16,500 --> 00:04:20,730
Then we call that the method that is number one.

54
00:04:21,000 --> 00:04:29,560
And we pass this list one as the parameter to it, and then we try to print the value of the list.

55
00:04:31,260 --> 00:04:36,450
Now, let us save this as C demo fifteen thought B vi.

56
00:04:36,630 --> 00:04:42,390
That's E drive HACKENBUSH and let us try to run this.

57
00:04:42,870 --> 00:04:46,970
So we are getting one, two, three and plus one more value is appended to it.

58
00:04:47,250 --> 00:04:49,200
So then you run the particular course.

59
00:04:49,200 --> 00:04:56,010
We have noticed that the metadata Skold return value isn't used to assign a new value to the variable

60
00:04:56,010 --> 00:04:57,090
that we have created.

61
00:04:57,390 --> 00:04:59,790
Instead, a list is modified directly.

62
00:05:00,010 --> 00:05:06,430
So when we ran the program, we get the value as one, two, three come up bitin, even though we are

63
00:05:06,430 --> 00:05:08,110
having two different variables.

64
00:05:08,350 --> 00:05:14,920
One is if we look at our program, one is our list one and one is the parameter that this parameter,

65
00:05:14,920 --> 00:05:20,020
one that contains separate references, they both refer to the same list.

66
00:05:20,290 --> 00:05:27,010
Now, this is why the append Biton matter called inside the function of the list, even after the function

67
00:05:27,010 --> 00:05:28,330
call has a record.

68
00:05:28,690 --> 00:05:30,400
So keep this behavior in mind.

69
00:05:30,400 --> 00:05:37,390
Forgetting that Biton handles list, variables this way can lead to some confusing box succumbing to

70
00:05:37,390 --> 00:05:41,920
using the copy poppy to duplicate a particular list value.

71
00:05:42,250 --> 00:05:48,970
Now, if you want to copy a list value, you can import the copy module to call the copy deep copy function,

72
00:05:49,360 --> 00:05:51,960
which returns a separate copy of the list.

73
00:05:52,300 --> 00:05:54,930
It is that that has been basically passed to it.

74
00:05:55,210 --> 00:06:03,200
For example, if we go for the let's close this domino and let's go back here and we try to create C

75
00:06:03,250 --> 00:06:06,270
over that's equal to zero comma.

76
00:06:06,370 --> 00:06:09,400
One, two, three, four, five, six, seven.

77
00:06:10,480 --> 00:06:12,590
Now we say import copy.

78
00:06:13,150 --> 00:06:21,580
Then we say another variable similar to that's equal to the US copy, not the copy, and we pass the

79
00:06:21,700 --> 00:06:23,310
VAT as the variable.

80
00:06:23,740 --> 00:06:29,550
Then we see the word to add the index of one.

81
00:06:29,620 --> 00:06:32,680
We want their python to be printed.

82
00:06:33,640 --> 00:06:40,500
And now we print the value of where we get zero one, two, three, four, five, six, seven.

83
00:06:40,870 --> 00:06:43,890
But now if we were to, we get it.

84
00:06:43,920 --> 00:06:46,840
Well, we have editors that zero one.

85
00:06:46,840 --> 00:06:49,270
Then we have Biton three, four, five, six, seven.

86
00:06:49,600 --> 00:06:56,800
Now because they copied our deep copy function, was used to copy the list in the variable that is there

87
00:06:57,010 --> 00:07:03,670
to where to when an item in two is changed, the original way is unaffected.

88
00:07:04,390 --> 00:07:07,000
We would be using this later in some sections.

89
00:07:07,000 --> 00:07:10,300
When we come back to some simple substitution ciphers.

90
00:07:10,960 --> 00:07:12,350
That's it from the station.

91
00:07:12,370 --> 00:07:13,300
Thank you very much.