WEBVTT 00:00.140 --> 00:00.710 Hello guys. 00:00.710 --> 00:03.140 So we are going to continue the discussion with respect to Python. 00:03.140 --> 00:06.680 And in this video we are going to discuss about lambda functions in Python. 00:06.710 --> 00:08.390 Now what exactly is lambda function? 00:08.390 --> 00:12.980 Lambda functions are small anonymous function defined using the lambda keyword. 00:12.980 --> 00:18.980 Now whenever we talk about anonymous function it can be basically said a function without a name. 00:18.980 --> 00:19.520 Right. 00:19.520 --> 00:25.730 So they can have any number of arguments but only one expression okay. 00:25.760 --> 00:29.960 And they are commonly used for short operation or as arguments to higher order function. 00:29.960 --> 00:33.170 Now here let me discuss about 2 to 3 keywords. 00:33.170 --> 00:34.580 First of all anonymous function. 00:34.610 --> 00:37.970 Anonymous function is basically a function without a name. 00:38.060 --> 00:44.090 And in order to create lambda function, we specifically require lambda keyword, and they can have 00:44.090 --> 00:47.300 any number of arguments, but only one expression. 00:47.300 --> 00:49.940 One expression basically means one logic, right? 00:49.940 --> 00:55.640 So here is one of the syntax I have given it over here like lambda arguments colon expression. 00:55.670 --> 01:00.520 Now let me just show you with some of the good practical examples so that you will be able to understand 01:00.520 --> 01:02.530 how does lambda function basically work? 01:02.560 --> 01:03.100 Okay. 01:03.160 --> 01:04.420 Now let me do one thing. 01:04.450 --> 01:04.630 Okay. 01:04.660 --> 01:10.090 Let me just go ahead and create a function which is called as definition a comma b okay. 01:10.150 --> 01:14.350 Now what I'm actually going to do over here is that I'll return a plus b. 01:14.440 --> 01:18.730 Now here obviously I've created a function which is taking two numbers. 01:18.730 --> 01:22.210 And here clearly you can just write two comma three. 01:22.210 --> 01:24.040 And here you'll be able to get an answer. 01:24.040 --> 01:26.860 Let's say the addition of two numbers two comma three is five. 01:27.070 --> 01:30.520 Now over here this is just a basic function right. 01:30.550 --> 01:36.070 And inside this you just have one expression one logic that you have written or one operation that you 01:36.100 --> 01:37.060 have written over here. 01:37.090 --> 01:37.450 Right. 01:37.480 --> 01:40.660 And for this you have created entirely one entire function. 01:40.660 --> 01:44.770 You have written the definition keyword a comma b, all these things you have specifically written. 01:44.800 --> 01:50.530 Now, what it says is that if you have just one expression and let's say you have multiple parameters 01:50.530 --> 01:56.590 over here, then instead of just creating a wholesome function over here, you can create a anonymous 01:56.590 --> 01:58.700 function, which is also called as lambda function. 01:58.730 --> 02:00.200 A function without a name. 02:00.290 --> 02:04.340 Now, if I really want to convert this function into a lambda function. 02:04.370 --> 02:05.150 See the syntax. 02:05.180 --> 02:07.790 Okay, so first of all I will go ahead and write lambda. 02:07.790 --> 02:12.260 And then the second parameter that over here it is asking is argument. 02:12.260 --> 02:15.170 So what are the arguments I am giving for this particular function. 02:15.200 --> 02:15.980 It is very simple. 02:15.980 --> 02:17.780 It is a comma b okay. 02:17.990 --> 02:22.940 Now with respect to a comma b I need to go ahead and write my expression. 02:22.940 --> 02:26.330 Expression is what task or what operation I am actually doing. 02:26.360 --> 02:32.930 Okay, so once I execute this so you can see that this becomes an anonymous function or lambda function 02:32.930 --> 02:33.410 also. 02:33.410 --> 02:36.020 So here I will just go ahead and create a variable. 02:36.020 --> 02:40.310 And this addition variable will be my lambda function. 02:40.340 --> 02:40.670 Okay. 02:40.700 --> 02:44.690 If you don't believe me let's go ahead and see the type of addition okay. 02:44.720 --> 02:46.010 And we'll try to print it. 02:46.010 --> 02:48.320 So here you can see it is a function okay. 02:48.350 --> 02:48.980 Lambda function. 02:48.980 --> 02:49.550 It is not saying. 02:49.550 --> 02:54.830 But here you can see that it is a kind of lambda function itself, the function without any specific 02:54.830 --> 02:55.190 name. 02:55.190 --> 02:58.270 Like we did not use any definition, we have just created a variable. 02:58.300 --> 03:06.250 Now, in order to call this okay, all I have to do is that just call this variable, give the parameters 03:06.250 --> 03:06.850 that I want. 03:06.880 --> 03:08.830 Let's say I want to give five comma six. 03:08.830 --> 03:10.720 And let me just go ahead and execute it. 03:10.720 --> 03:15.160 So here you can see automatically with the help of this lambda expression entirely. 03:15.160 --> 03:17.470 The operation is basically happening here. 03:17.470 --> 03:18.520 These are my arguments. 03:18.520 --> 03:20.800 And this is the expression that we have specifically given. 03:20.830 --> 03:21.190 Right. 03:21.220 --> 03:27.340 So I hope you are able to understand and how beautifully just by understanding the syntax we have just 03:27.340 --> 03:29.770 given the values over here and you are able to see the answer. 03:29.800 --> 03:31.450 Okay, let me do one more thing. 03:31.480 --> 03:31.630 Okay. 03:31.660 --> 03:33.310 Let me just go ahead and create one function. 03:33.310 --> 03:36.640 Let's say uh, I'll create a function which is called as even. 03:36.670 --> 03:37.180 Okay. 03:37.180 --> 03:40.030 And here I give a number okay. 03:40.240 --> 03:43.930 Now with respect to this number I'll just go ahead and put a condition. 03:43.930 --> 03:46.570 If num modulus two is double equal to zero. 03:46.570 --> 03:49.450 So in short I'm just checking whether the number is even or odd. 03:49.480 --> 03:52.600 Then I'm just going to return the value as true okay. 03:52.810 --> 03:53.620 Perfect. 03:53.710 --> 03:56.770 Now let me just go ahead and give the value. 03:56.770 --> 03:58.630 So here I'm going to call a function right. 03:58.660 --> 03:59.530 Even 24. 03:59.530 --> 04:01.870 So here I'm actually going to get true okay. 04:01.900 --> 04:06.640 Now similarly if I want to convert this into a lambda function let me just go ahead and create my variable. 04:06.670 --> 04:09.310 Even one I'll be using lambda. 04:09.340 --> 04:10.600 I'll give my parameters. 04:10.600 --> 04:13.630 What is my parameters arguments that I need to give only num. 04:13.630 --> 04:19.210 Then I'll write my colon and all I have to basically do is write my expression and the expression is 04:19.210 --> 04:19.690 over here. 04:19.690 --> 04:23.500 Simple num modulus two is double equal to zero. 04:23.530 --> 04:27.850 Right now this even one becomes my variable. 04:27.850 --> 04:30.520 So now if I go ahead and just go ahead and write 12. 04:30.550 --> 04:34.930 Now it is going to give me true because 12 is basically an even number. 04:34.960 --> 04:35.320 Right. 04:35.320 --> 04:37.390 And here you can write any variable. 04:37.390 --> 04:40.870 It is not necessary that you only need to write number okay. 04:41.440 --> 04:45.550 You can write A, you can write B, you can write C, whatever things you specifically want to write 04:45.580 --> 04:46.060 okay. 04:46.090 --> 04:48.040 Based on that you can actually do that. 04:48.070 --> 04:51.190 Now let's try with some more examples. 04:51.190 --> 04:54.340 And here this time I'm going to take multiple parameters. 04:54.370 --> 04:54.820 Okay. 04:54.850 --> 04:58.930 So let me just go ahead and create one function which is called as addition. 04:58.930 --> 04:59.680 Let's say. 04:59.680 --> 05:03.400 And here I'm actually going to give my x comma y comma z. 05:03.400 --> 05:08.650 So these are my parameters I'm just going to return x plus y plus z okay. 05:08.680 --> 05:13.330 Now when I'm actually doing this if I am calling my addition function. 05:13.450 --> 05:16.180 So here you will be able to see that I'll give my values. 05:16.180 --> 05:19.030 So let's say 1213 comma 14. 05:19.150 --> 05:21.370 If I execute it the sum is basically 39. 05:21.370 --> 05:22.180 Now let me see. 05:22.210 --> 05:26.290 Let me show you how you can actually convert this into an lambda function. 05:26.290 --> 05:28.210 I'll create a addition one variable. 05:28.210 --> 05:31.060 And now I will be using a lambda function. 05:31.060 --> 05:36.190 And with respect to this specific lambda function what I am actually going to do I'm going to give my 05:36.190 --> 05:38.080 arguments which all is required. 05:38.080 --> 05:39.070 Let's say x, y, z. 05:39.100 --> 05:43.150 Then I will be giving the colon and I only have to write the expression. 05:43.150 --> 05:46.180 And I have already shown you how to write it down x plus y plus z. 05:46.210 --> 05:46.660 Right. 05:46.690 --> 05:48.070 So this is it. 05:48.070 --> 05:50.850 And if I go ahead and call my addition additions one. 05:50.850 --> 05:57.060 So here you'll be able to see that if I give my values 12, 13 and 14, I should be able to get 39, 05:57.090 --> 05:57.600 right? 05:57.600 --> 06:02.280 So through this way, I am not wasting much time to probably create a function. 06:02.280 --> 06:07.080 Instead, just by using a lambda function or anonymous function, I am able to do all this kind of expression, 06:07.200 --> 06:08.280 uh, operations. 06:08.280 --> 06:08.670 Right? 06:08.700 --> 06:13.530 Again, to repeat guys, a lambda function where only a single expression is there, we can actually 06:13.530 --> 06:16.350 convert that entire function into a lambda function itself. 06:16.680 --> 06:23.010 Uh, lambda function has more amazing features, but for that we really need to understand about map. 06:23.010 --> 06:26.400 And there is there are two function which is called as map and filter. 06:26.400 --> 06:30.930 So in the upcoming videos we will be discussing about this map function and filter function. 06:30.930 --> 06:37.440 And I will just give you one example right now just to make you understand, uh, what exactly map and 06:37.440 --> 06:38.550 filter basically does. 06:38.580 --> 06:39.150 Okay. 06:39.180 --> 06:44.730 So yes, in the next video we'll be discussing more, but I just want to give you the expression of 06:44.730 --> 06:46.260 power of lambda function with map. 06:46.290 --> 06:46.650 Okay. 06:46.650 --> 06:50.930 So let's say I want to probably go ahead and create a list, right? 06:50.930 --> 06:54.590 And with respect to the list, I have values like one, two, three, four, five, six. 06:54.620 --> 06:55.160 Okay. 06:55.190 --> 07:00.020 Now let's say that I want to find the square of each and every number. 07:00.050 --> 07:00.590 Right? 07:00.590 --> 07:04.910 If I want to find the square of each and every number, or let's say I want to just go and see that, 07:04.940 --> 07:10.520 hey, uh, uh, you know, uh, let's say I'll just go ahead and create a variable, let's say squared 07:10.520 --> 07:11.420 underscore numbers. 07:11.450 --> 07:12.020 Okay. 07:12.200 --> 07:15.020 Now in order to find out square for every number. 07:15.020 --> 07:15.560 Right. 07:15.590 --> 07:17.690 What is the kind of function we will define. 07:17.690 --> 07:21.230 Let's say I'm going to define definition square okay. 07:22.490 --> 07:23.360 Square. 07:24.890 --> 07:28.430 And here I am going to give my numbers. 07:28.460 --> 07:30.380 Or let me just give single number. 07:30.410 --> 07:31.670 Then what this is going to do. 07:31.700 --> 07:36.350 Return number double star square. 07:36.380 --> 07:36.920 Right. 07:37.130 --> 07:39.740 So here we are just giving a square. 07:40.340 --> 07:43.400 And if I give two number I'm going to get the square of that particular number. 07:43.400 --> 07:44.150 This is fine. 07:44.150 --> 07:45.710 And this is only for one number. 07:45.740 --> 07:50.230 Right now if I am giving for a list of number, then what I have to do, I'll give this number as a 07:50.230 --> 07:50.620 parameter. 07:50.650 --> 07:54.460 Over here I'll write a for loop, iterate through each and every number and do this particular operation 07:54.460 --> 07:55.780 and return it right. 07:55.930 --> 07:59.770 But is there a better way instead of iterating it? 07:59.770 --> 08:03.790 Truly, you know, probably writing more couple of lines of code for this, right? 08:03.820 --> 08:04.810 Is there a better way? 08:04.810 --> 08:08.020 So we can specifically use this map function map function. 08:08.020 --> 08:10.210 What it does is that it applies. 08:10.330 --> 08:17.950 It applies a function to all items in a list. 08:17.980 --> 08:19.450 Okay, right. 08:19.480 --> 08:23.020 Or any collection also okay, so what does this basically mean. 08:23.020 --> 08:25.780 And I will show you along with the map function okay. 08:25.780 --> 08:28.360 So now sorry along with the lambda function. 08:28.390 --> 08:30.520 Now let me just go ahead and create this lambda function. 08:30.520 --> 08:34.150 So first of all I will go ahead and write lambda I know what is my operation. 08:34.150 --> 08:35.770 My operation is basically squaring right. 08:35.800 --> 08:37.660 So I will create a argument. 08:37.660 --> 08:42.130 So argument I will be requiring a number x and the expression will be x square okay. 08:42.160 --> 08:48.050 So this basically becomes lambda right Now map basically requires. 08:48.050 --> 08:50.870 The first parameter in map is basically a function. 08:50.870 --> 08:53.180 The second parameter is iterables. 08:53.180 --> 08:55.400 So this actually is my lambda function. 08:55.400 --> 08:57.290 Or you can also call this particular function. 08:57.290 --> 08:59.900 But right now I'm giving my lambda function over here. 08:59.900 --> 09:04.100 And the second parameter that I'm actually going to give is nothing but my numbers. 09:04.100 --> 09:04.640 Right. 09:04.640 --> 09:07.880 So here is basically my map right now. 09:07.880 --> 09:13.310 At the end of the day, if I execute this, this basically creates a map object at this particular memory 09:13.310 --> 09:14.000 location. 09:14.000 --> 09:20.270 And map usually uses a lazy loading technique that basically means still it has not completely initialized. 09:20.270 --> 09:23.690 So to make it initialized I will convert this into a list. 09:23.720 --> 09:29.060 Now see the magic okay, for every number in this particular list, automatically you are able to get 09:29.060 --> 09:30.110 the square right. 09:30.140 --> 09:31.250 Isn't it beautiful? 09:31.250 --> 09:34.880 So I will just try to show you like how we can use Map Lambda. 09:34.880 --> 09:37.850 And there is also one more function which is called as filter. 09:37.880 --> 09:38.150 Right. 09:38.150 --> 09:41.000 And I'll explain all these things in my upcoming videos. 09:41.000 --> 09:42.440 So yes this was it from my side. 09:42.470 --> 09:43.940 I will see you all in the next video. 09:43.940 --> 09:44.570 Thank you.