1
00:00:00,420 --> 00:00:03,120
We are going to discuss Biton iterators.

2
00:00:04,280 --> 00:00:11,870
So iterators are present in Baton and they are mostly implemented within four loop's comprehensions,

3
00:00:12,080 --> 00:00:16,210
generators, etc., but hidden in plain sight.

4
00:00:16,910 --> 00:00:23,780
So a delegate in Python is simply an object that can iterated upon an object which will return.

5
00:00:23,780 --> 00:00:26,220
Data are the one element at the time.

6
00:00:26,720 --> 00:00:34,250
So this iterator will be operating on a sequence of elements and each and every iteration it will pick

7
00:00:34,250 --> 00:00:35,660
up one element at a time.

8
00:00:36,140 --> 00:00:43,010
So it's written in Python is simply an object that can be iterated upon an object which is which will

9
00:00:43,010 --> 00:00:45,920
return data one element at a time.

10
00:00:46,460 --> 00:00:51,730
Technically speaking, Biton iterator object must implement two special methods.

11
00:00:51,830 --> 00:00:57,030
So what are the two special methods that is understood, understood, etre, underscore, underscore,

12
00:00:57,050 --> 00:01:01,520
method and underscore, underscore, next, underscore, underscore method.

13
00:01:01,760 --> 00:01:07,390
So it's the method and the next method collectively called the iterator protocol.

14
00:01:07,610 --> 00:01:11,360
So it's a method that is to retrieve their respective value.

15
00:01:11,360 --> 00:01:15,610
At the next, he will check whether the next element is there in the sequence or not.

16
00:01:17,660 --> 00:01:25,310
So an object is called iterable, if we can get an iterator from it, and most of the built in containers

17
00:01:25,310 --> 00:01:33,090
in Biton, like the least double strings, etc, are iterable because we can extract we can get iterator

18
00:01:33,110 --> 00:01:40,130
from it, that it did a function which in turn call that etre that is understood, understood, itr

19
00:01:40,130 --> 00:01:44,810
underscore, underscore method returns and iterator from them.

20
00:01:45,280 --> 00:01:52,130
The next that is underscore, underscore, next underscore, underscore method must return the next

21
00:01:52,130 --> 00:02:00,850
item in the sequence on the reaching at the end and in the subsequent calls it must raise stop iteration.

22
00:02:01,250 --> 00:02:07,190
So whenever we are having no item in the in the iterator remaining.

23
00:02:07,340 --> 00:02:12,730
But you are calling this underscore, underscore next underscore the underscore method, then one one

24
00:02:12,740 --> 00:02:15,660
exception will be raised and that is a stop iteration.

25
00:02:16,220 --> 00:02:23,090
So let us go for one practical demonstration to show you that how this python iterators can easily be

26
00:02:23,090 --> 00:02:25,220
implemented in python coding.

27
00:02:25,400 --> 00:02:27,890
So here is the demonstration for you.

28
00:02:28,730 --> 00:02:35,780
Iterators are very common in our python programming language and these are elegantly implemented within

29
00:02:35,780 --> 00:02:43,790
our four loops, generators, comprehensions, etc. but hidden in plain sight and iterated in Python

30
00:02:43,790 --> 00:02:45,470
is nothing but an object.

31
00:02:45,620 --> 00:02:50,570
And this object will return detA one at a time during our iteration.

32
00:02:50,670 --> 00:02:56,720
Obviously, if some data is available, then it will return the data, otherwise it will throw some

33
00:02:56,720 --> 00:02:57,280
exception.

34
00:02:57,800 --> 00:03:02,150
So technically speaking, Python Étretat object must implement two special methods.

35
00:03:02,160 --> 00:03:03,500
One is the next method.

36
00:03:03,800 --> 00:03:07,670
So Kano's we call does underscore, underscore, next underscore the underscore method.

37
00:03:07,880 --> 00:03:13,340
And out of the one is the ITR method that is actually underscored, underscored, etre underscore,

38
00:03:13,340 --> 00:03:20,240
underscore the method and collectively they will be known as the iterator protocol and object is called

39
00:03:20,240 --> 00:03:24,380
iterable if we can get an iterator from it.

40
00:03:24,830 --> 00:03:31,910
Most of the building content in our python, like our string, like our top, at least having they are

41
00:03:31,910 --> 00:03:39,740
nothing but eatables that entire method or the ITR function, which in turn called the itr underscore,

42
00:03:39,740 --> 00:03:45,130
underscore etre underscored underscore method returns and iterator from them.

43
00:03:45,530 --> 00:03:51,180
So let us go through this example and to discuss the property of this iterator.

44
00:03:51,590 --> 00:03:58,310
So here you see here to define one list here and this item start from using this method from this it

45
00:03:58,490 --> 00:04:06,020
from this list we are getting one iterated and to access that data from this iterator, we are using

46
00:04:06,020 --> 00:04:07,490
the method next here.

47
00:04:07,820 --> 00:04:10,040
So either we can use this next already.

48
00:04:10,520 --> 00:04:14,720
So do the syntax to retrieve elements from this iterator.

49
00:04:14,720 --> 00:04:16,490
That is our return address.

50
00:04:16,490 --> 00:04:21,250
We can write our return dot, underscore, underscore, next underscore, underscore method.

51
00:04:21,270 --> 00:04:23,110
So anyone we can use that one.

52
00:04:23,510 --> 00:04:28,390
So here to see the list is containing data that is forty four, seven, seven, 11 and 33.

53
00:04:28,730 --> 00:04:36,710
So for the next unretiring 44 next mean there is seventy seven next element which will be retrieved

54
00:04:36,710 --> 00:04:40,660
here is eleven next eleven which will be added to here 33.

55
00:04:41,000 --> 00:04:44,550
So now we have got all the four elements now.

56
00:04:44,610 --> 00:04:48,620
Now if we go for next hour, later it will raise one exception.

57
00:04:48,890 --> 00:04:51,740
So let let us go for the execution of this block.

58
00:04:52,820 --> 00:04:59,930
So here we are having forty four, seventy seven, 11 and 33 because the elements were 44, 77, 11

59
00:04:59,930 --> 00:05:00,740
and 33.

60
00:05:01,040 --> 00:05:09,650
So when we execute that print next hour, greater than 44 was retrieved and next print next hour after

61
00:05:09,670 --> 00:05:14,810
we execute this method, then 77 has been retrieved from this iterator.

62
00:05:15,050 --> 00:05:16,850
That is our return next time.

63
00:05:16,860 --> 00:05:17,830
Eleven next time.

64
00:05:17,840 --> 00:05:18,500
Thirty three.

65
00:05:18,500 --> 00:05:22,850
Now, if I execute this one, I should not put this one in comment.

66
00:05:22,850 --> 00:05:28,880
If I execute this one, then one exception will be there and there is a stop iteration and this will

67
00:05:28,880 --> 00:05:32,390
raise no items left, as we mentioned in the comment.

68
00:05:32,600 --> 00:05:36,050
And so next hour it will produce this error.

69
00:05:36,050 --> 00:05:37,520
That is a stop iteration.

70
00:05:38,120 --> 00:05:39,590
So let us go for another one.

71
00:05:40,370 --> 00:05:42,220
So create a custom iterator.

72
00:05:42,590 --> 00:05:45,980
So here we are defining one class that is the power of two.

73
00:05:46,310 --> 00:05:49,760
And here we are having this document documentation string.

74
00:05:49,980 --> 00:05:52,820
In short, we can call it as dark string.

75
00:05:53,120 --> 00:05:58,970
So it should be enclosed either within a single class or triple double quotes.

76
00:05:59,270 --> 00:06:05,330
So it is also known as a block comment, and it should be the first intended, intended statement in

77
00:06:05,330 --> 00:06:06,110
our class.

78
00:06:06,470 --> 00:06:11,420
So next, we are having this constructor that is our underscore, underscore in it, underscore, underscore.

79
00:06:11,750 --> 00:06:15,070
So here you are defining this, Max, and this is a goal.

80
00:06:15,080 --> 00:06:16,850
Digital is the default argument.

81
00:06:17,410 --> 00:06:22,690
So whatever the value will be passing that will be assigned to this Max instance variable, so here

82
00:06:22,690 --> 00:06:28,030
we are just defining this underscore, underscore, Peter, underscore, underscore method and similarly

83
00:06:28,240 --> 00:06:31,520
this underscore, underscore, next underscore, underscore method.

84
00:06:31,750 --> 00:06:36,380
So these two methods we are defining here, so self-taught in physical digital.

85
00:06:36,460 --> 00:06:42,230
So in another instance, rideable is getting initialized with the Vallecito and then having this next.

86
00:06:42,250 --> 00:06:49,180
So if self got in is less than equal to Max, then the Israelis are due to start start.

87
00:06:49,480 --> 00:06:55,690
That is due to the power of self-taught ends up in will be assigned to the result and self-taught and

88
00:06:55,690 --> 00:06:58,440
will be increased by one and the result will be returned.

89
00:06:58,450 --> 00:07:04,870
Otherwise that else in the part we are going for stop iteration where it is this error, there is a

90
00:07:04,870 --> 00:07:05,890
stop iteration.

91
00:07:06,580 --> 00:07:10,260
So now here at first we are going to print this dark string.

92
00:07:10,270 --> 00:07:16,600
There is a documentation string and then triple single codes can also be included within the triple

93
00:07:16,600 --> 00:07:17,370
double codes.

94
00:07:17,590 --> 00:07:24,100
So whenever we are printing this, this one, there is a part of two that is a class named Underscore,

95
00:07:24,100 --> 00:07:26,030
underscore, underscore, underscore.

96
00:07:26,050 --> 00:07:28,060
You can see that it is printing.

97
00:07:28,900 --> 00:07:30,030
Let us go for this.

98
00:07:30,040 --> 00:07:35,560
It is printing this respective string that is a class to implement and iterator of powers of two.

99
00:07:35,800 --> 00:07:38,940
So that string whatever is discussed or defined here.

100
00:07:39,370 --> 00:07:40,490
So it has got printed.

101
00:07:40,930 --> 00:07:42,310
So now we are going for this.

102
00:07:42,730 --> 00:07:44,780
It is equal to power of two four.

103
00:07:44,800 --> 00:07:47,340
So now this fall will be assigned to Max.

104
00:07:47,650 --> 00:07:49,000
This will be assigned to Max.

105
00:07:49,000 --> 00:07:50,660
So Max has got the value for here.

106
00:07:51,100 --> 00:07:55,180
So now we are going for this bicycle to iterate.

107
00:07:55,390 --> 00:07:57,400
So we are going for this next day.

108
00:07:57,440 --> 00:07:57,970
Next day.

109
00:07:57,970 --> 00:07:58,390
The next day.

110
00:07:58,390 --> 00:07:59,920
It is going on going on printing.

111
00:08:00,140 --> 00:08:04,000
That is to the part of zero because Ania's having the initial value zero here.

112
00:08:04,420 --> 00:08:08,890
So to zero the result will become one and return result.

113
00:08:08,900 --> 00:08:10,940
So that result will be printed as one.

114
00:08:11,350 --> 00:08:17,560
So next time this end has got increased by one or two to one, the result will have the value to and

115
00:08:17,560 --> 00:08:18,340
return the result.

116
00:08:18,340 --> 00:08:20,180
That means it will return the value to here.

117
00:08:20,200 --> 00:08:25,290
So too is getting printed because we have called this next day from this print method.

118
00:08:25,540 --> 00:08:30,830
So now next time the value of N will become too so to become four.

119
00:08:30,850 --> 00:08:35,170
So this will have the value for and the result will be returned and that will get printed.

120
00:08:35,200 --> 00:08:40,000
So in this way, I'm getting this one as one to four as output.

121
00:08:40,420 --> 00:08:45,490
So I think you are getting this idea how this method, which is having this in it, there is a constructor,

122
00:08:45,490 --> 00:08:49,270
this ITR method, the next method and the respective object.

123
00:08:49,270 --> 00:08:51,010
We are defined under the class.

124
00:08:51,010 --> 00:08:52,060
That is our aim.

125
00:08:52,510 --> 00:08:58,420
So this Max has got initialized with the value for which has been passed as a parameter to this constructor.

126
00:08:58,780 --> 00:09:01,210
Then out of this eight, we are creating one item.

127
00:09:01,420 --> 00:09:06,880
So this iterator is this one I and from Iterator we can pick up the next Palouse.

128
00:09:07,060 --> 00:09:08,410
So there is a next of I.

129
00:09:08,410 --> 00:09:10,090
So this method is getting called.

130
00:09:10,510 --> 00:09:15,760
So we can also call it, as I underscore, underscore, next underscore, underscore method.

131
00:09:15,790 --> 00:09:17,170
So let me bring it here.

132
00:09:17,170 --> 00:09:23,590
So I dot underscored, underscore, next underscore, underscore methods to also we can print it.

133
00:09:24,430 --> 00:09:27,720
So now let me, let me go for the execution of the same.

134
00:09:27,730 --> 00:09:29,530
So I'm just erasing this part.

135
00:09:29,710 --> 00:09:30,790
It is not required.

136
00:09:34,630 --> 00:09:40,660
OK, so now if we execute the same I'm getting the same output because next day is actually executing

137
00:09:40,660 --> 00:09:43,920
IDOT underscored, underscore, next underscore, underscore method.

138
00:09:44,500 --> 00:09:49,310
So next week we are going for creating a infinite custom iterator.

139
00:09:49,660 --> 00:09:51,730
So in this case, this is our Doch string.

140
00:09:51,730 --> 00:09:54,020
The name of the class is Infinite Etre.

141
00:09:54,400 --> 00:09:58,680
And here we are having this method literally of define the next we have defined.

142
00:09:59,080 --> 00:10:01,190
So this is the infinite eater object.

143
00:10:01,190 --> 00:10:03,310
The class object is I from the site.

144
00:10:03,310 --> 00:10:08,810
We're creating one iterator using the method etre and then we are going for this next E!

145
00:10:09,190 --> 00:10:11,740
So here you see the NUM has got the value one.

146
00:10:12,010 --> 00:10:16,000
So NUM is equal to num num num has got the value one here.

147
00:10:16,120 --> 00:10:18,400
Sultanahmet is equal to two.

148
00:10:18,670 --> 00:10:24,070
So in this way it will go on creating because there is no logic is there, to stop this one.

149
00:10:24,070 --> 00:10:30,130
It will go on creating, just incrementing this value of NO2 each and every time and then returning

150
00:10:30,130 --> 00:10:32,830
that number is a previous value of NUM will be returned.

151
00:10:33,220 --> 00:10:37,930
So now we are having this next day, the next day, next in this way, if you go on all in the next

152
00:10:37,930 --> 00:10:38,430
method.

153
00:10:38,620 --> 00:10:41,100
So at first the number was having the value one.

154
00:10:41,410 --> 00:10:44,030
So this one will be assigned to NUM, which will be returned.

155
00:10:44,050 --> 00:10:45,470
So that is getting printed.

156
00:10:45,700 --> 00:10:48,730
So one will get printed, then three, then five and seven.

157
00:10:48,970 --> 00:10:51,370
In this way the values will go on printing.

158
00:10:51,370 --> 00:10:53,320
So it has got no dominating logic.

159
00:10:53,560 --> 00:10:57,830
So that's why it is infinite etre, the name of the class has been given accordingly.

160
00:10:58,270 --> 00:11:04,210
So from this demonstration, you are getting this idea that how this iterator can play its role in our

161
00:11:04,210 --> 00:11:05,090
Python programming.

162
00:11:05,650 --> 00:11:06,880
Thanks for watching this video.