Identity Operators

Quick reference

• 00:04 In this video I want to look at identity operators, specifically is and is not.
• 00:09 So we've already looked at the comparison operator to do equal to which is double
• 00:13 equal to.
• 00:14 So for instance if we have "John" equal to "John"
• 00:19 if we print this whole thing out we run this,
• 00:23 it's going to be true because John equals John.
• 00:28 So we've already sort of established this.
• 00:30 And we can also do not equal to as well.
• 00:33 But there's another way to do this as well, and that's the is and
• 00:36 is not identity operators.
• 00:38 So let's just walk through those here, I'll show you.
• 00:40 Let's create a variable called name and we'll call it John and
• 00:43 then let's do name_2, let's say that's also John.
• 00:47 So behind the scenes, Python will convert these strings into a unique identifier,
• 00:54 a unique identity number, right, a big long integer.
• 00:59 And we can see what that identity number is,
• 01:02 what that identifier is, by typing in id and then the variable name.
• 01:07 Now if we want to print this to the screen like everything else,
• 01:10 we just wrap it in a print function here.
• 01:12 And we get this whole big number.
• 01:14 And every time you run this you're going to get a different number,
• 01:17 because every time it's saving it to a different space in memory.
• 01:20 But we can take this statement and do another one with our second variable.
• 01:26 And you can see, if you compare these,
• 01:28 they are exactly the same because the strings are exactly the same.
• 01:32 If we run it again we'll get two different ones but they are still the same.
• 01:36 Well if we change our variable, our second variable, let's say Elder,
• 01:40 my name is John Elder.
• 01:41 If we run this it's mostly the same up until about right here in the last
• 01:46 three digits, 760, last three digits 856.
• 01:49 So we have a different identity number, a different memory space where
• 01:52 these are being stored because they're different things.
• 01:55 So we can actually compare these two identity numbers using identity operators,
• 02:00 specifically is and is not.
• 02:02 Let's go ahead and do that, first let's print it and
• 02:08 let's go name is, name_2.
• 02:11 And this is just like saying equal to, with our comparison operator, but
• 02:15 instead of saying equal to, we're saying is, because we're comparing identities.
• 02:20 So if we save this and run it, we see false, because John and
• 02:24 Elder are not the same identity numbers.
• 02:27 We can also do the opposite, is not, we save this, true.
• 02:31 So if we change this back to John, save it.
• 02:35 Now it's going to be false because name is not, this is false because they are true.
• 02:40 We can test for trueness, is name equal to name_2?
• 02:44 Name is name_2, put that question mark at the end, name is name_2,
• 02:48 like you're asking a question.
• 02:50 Save this, run it, true.
• 02:53 So we can do the same thing with an if statement.
• 02:56 We can say if (name is name_2): print ("They're the same!").
• 03:03 Save this and run it, we're going to see they're the same.
• 03:07 So those are identity operators.
• 03:08 Sometimes you're going to want to use just regular double equal to or not equal to.
• 03:14 Other times you're going to want to test for that long integer,
• 03:17 unique identity number in that case you use is or is not.
• 03:21 So that's identity operators.
• 03:22 In the next video we're going to look at while loops.

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