1
00:00:00,000 --> 00:00:11,160
So, there are two more useful operators

2
00:00:11,160 --> 00:00:13,665
for producing Boolean values.

3
00:00:13,665 --> 00:00:18,995
First, we're going to go over in and then we're going to go over its opposite not in.

4
00:00:18,995 --> 00:00:24,735
So, in checks to see if the thing on the left is a member of the thing on the right.

5
00:00:24,735 --> 00:00:26,640
So for example here,

6
00:00:26,640 --> 00:00:29,970
suppose that we have a string apple and we want to

7
00:00:29,970 --> 00:00:33,795
check if some substring is contained in that string.

8
00:00:33,795 --> 00:00:36,770
So, the value of this expression is going to be true,

9
00:00:36,770 --> 00:00:40,340
because the character p is an apple.

10
00:00:40,340 --> 00:00:43,370
The value of this expression is going to be false,

11
00:00:43,370 --> 00:00:46,430
because the character i is not an apple.

12
00:00:46,430 --> 00:00:49,640
The value of this expression is going to be true,

13
00:00:49,640 --> 00:00:53,675
because the substring AP is an apple.

14
00:00:53,675 --> 00:00:57,275
And the value of this expression is going to be false,

15
00:00:57,275 --> 00:00:59,585
because PA is not an apple.

16
00:00:59,585 --> 00:01:03,845
So, I should get true, false, true, false.

17
00:01:03,845 --> 00:01:09,815
So, if I print out is a in the string a then I should get true,

18
00:01:09,815 --> 00:01:13,160
because yes, even though these two things are the same,

19
00:01:13,160 --> 00:01:16,235
technically this is inside of this.

20
00:01:16,235 --> 00:01:19,045
Same thing with if I spell out apple.

21
00:01:19,045 --> 00:01:23,435
So, the value of both of these expressions will be true.

22
00:01:23,435 --> 00:01:29,180
Somewhat weirdly, if I check to see if an empty string is contained in any other string,

23
00:01:29,180 --> 00:01:30,665
then I'm going to get true.

24
00:01:30,665 --> 00:01:34,320
So, is this empty string inside of the string a?

25
00:01:34,320 --> 00:01:36,805
It's debatable what the answer should be,

26
00:01:36,805 --> 00:01:40,625
but the way that Python evaluates this expression I get true.

27
00:01:40,625 --> 00:01:44,675
So, if I check to see if this empty string is in the string apple,

28
00:01:44,675 --> 00:01:47,200
I'm going to get true for this as well.

29
00:01:47,200 --> 00:01:51,170
Now, the opposite of in is not in.

30
00:01:51,170 --> 00:01:55,400
So, if I check to see if something is not in another string,

31
00:01:55,400 --> 00:01:58,430
then I'm going to get true if it's not in that string.

32
00:01:58,430 --> 00:02:01,660
So, x is not in apple.

33
00:02:01,660 --> 00:02:05,900
So, the value of this overall expression is going to be

34
00:02:05,900 --> 00:02:10,460
true because the string apple doesn't contain the character x.

35
00:02:10,460 --> 00:02:14,630
So, somewhat confusingly, this not has

36
00:02:14,630 --> 00:02:20,230
the same spelling as something like not Boolean expression,

37
00:02:20,230 --> 00:02:23,585
but these are entirely different things.

38
00:02:23,585 --> 00:02:28,415
They have the same function which is reversing the value of the Boolean expression,

39
00:02:28,415 --> 00:02:31,820
so I'm saying not B is going to be true if B is

40
00:02:31,820 --> 00:02:36,635
false in not in is going to be true if this is not in it,

41
00:02:36,635 --> 00:02:41,405
but to Python, there are different kinds of expressions.

42
00:02:41,405 --> 00:02:47,615
So, I just want to also illustrate that in also works with lists.

43
00:02:47,615 --> 00:02:52,880
So, here if I check to see if this item is in this list,

44
00:02:52,880 --> 00:02:56,450
I'm going to get the value false because it's

45
00:02:56,450 --> 00:03:00,230
checking to see is there an item in this list,

46
00:03:00,230 --> 00:03:03,485
whose value is just the string A,

47
00:03:03,485 --> 00:03:06,710
even though I have some strings that happen to contain

48
00:03:06,710 --> 00:03:10,780
As there's no item whose value is equal to A,

49
00:03:10,780 --> 00:03:13,950
so I get false for this expression.

50
00:03:13,950 --> 00:03:17,290
That's all for now until next time.