WEBVTT 00:00.950 --> 00:09.470 Right now, we would talk about the lamda functions and how we can use them along with MAP Reduce and 00:09.470 --> 00:09.950 fatal. 00:10.980 --> 00:15.450 So first of all, let us discuss what lambda functions actually are. 00:16.380 --> 00:27.420 Lambda functions are one of the python's most useful tools and these are really very difficult and confusing 00:27.540 --> 00:28.550 for the beginners. 00:29.190 --> 00:34.950 So it is very important to pay attention and understand this concept, because once you understand this, 00:34.950 --> 00:36.360 it will be very helpful. 00:38.380 --> 00:48.520 So no function is used to create anonymous functions, so we have been using the def keyboard to create 00:48.520 --> 00:57.990 different functions, I would create a function system and this would basically help me to add to numbers. 00:58.030 --> 01:00.250 So let's say I have no equal maybe. 01:00.520 --> 01:02.170 And I would simply say. 01:03.320 --> 01:13.370 The tone and I would say A plus B, so this function would allow me to read on the some of these two 01:13.380 --> 01:21.050 values so I can any time you sums and give the two there, one or two, and it will simply give me the 01:21.050 --> 01:21.980 result of this thing. 01:23.370 --> 01:32.900 Now it is very easy to use this and it might be a little of you can say find the woman to write this 01:33.230 --> 01:38.060 function and maybe I might use this several number of times. 01:39.210 --> 01:45.210 But there could be a situation when I don't really want to you several functions. 01:45.420 --> 01:48.960 I do want to keep the method aside. 01:49.080 --> 01:56.970 I do want to keep the functionality aside, but I don't really want to reuse this thing again and again. 01:57.180 --> 02:03.390 So what I can do is I can quickly create a small function, which I can use at that time and then completely 02:03.390 --> 02:04.130 forget about. 02:04.920 --> 02:08.250 So that is what lamda function allows me to. 02:10.440 --> 02:16.420 So Lamda is a single expression and it is not a block statement. 02:16.650 --> 02:22.170 So usually when we have the lambda functions or let's say when we have any of the functions. 02:33.300 --> 02:39.340 Let us say I am creating this function sum's, so I am writing these three lines of code. 02:39.930 --> 02:46.620 But in case of a lambda expression it I don't need to write these so many lines of code. 02:46.620 --> 02:49.440 I just need to write a small expression here. 02:50.030 --> 02:56.580 OK, so let us see how we can construct this lambda expression and how we can use this. 02:57.290 --> 02:59.430 OK, so let us see. 02:59.430 --> 03:00.960 I want to create. 03:02.280 --> 03:07.080 Alamdar function, so what I can simply do is I can send these right lamda. 03:09.180 --> 03:18.780 And with Lamda, I want to read the argument, which I want to give, so let us say I want to have equal 03:18.810 --> 03:22.440 maybe these are the two arguments which I wanted to be. 03:23.190 --> 03:29.760 And what I want to give out of what I want to now is what I write next up of this. 03:30.390 --> 03:31.470 So I give all. 03:31.710 --> 03:33.950 And after this I simply say E-Plus. 03:34.500 --> 03:39.420 So I just want to read on E-Plus V and A and B is what I'm speaking from. 03:40.380 --> 03:47.340 So this is a very small lambi expression which I can use any number of times. 03:48.090 --> 03:53.340 OK, now this lambda expression V will not be using like this. 03:54.330 --> 03:57.460 OK, we will not be giving any lame name to it. 03:57.630 --> 04:00.030 So what I can do is I can see something like. 04:01.260 --> 04:02.680 See love. 04:04.140 --> 04:15.470 And I can create this kind of thing, so whenever I do something Laci, I do and I give simplicity to 04:15.480 --> 04:19.080 grandma if I do it so it will give the desired back to me. 04:19.090 --> 04:21.560 But this is what I actually don't want to do. 04:21.570 --> 04:23.160 I don't want to give anything to it. 04:23.400 --> 04:28.080 This is the main concept of lamda function that I don't want to create a mean function. 04:28.470 --> 04:32.130 If I wanted to create a new function, I would have used this only. 04:32.990 --> 04:40.860 OK, so for lambda expression, what we want to do is we don't want this and we don't want this also. 04:41.840 --> 04:44.130 So this is something which I don't really want. 04:44.630 --> 04:54.710 What I want is I want to use this along with any functions, which is either map reduce or forgive. 04:55.490 --> 05:03.080 OK, now let's try to understand what my buzz, what reveals does what filter does and how we can use 05:03.080 --> 05:04.700 Langbein concurrence with this. 05:05.910 --> 05:13.920 OK, you can use other functions also with my produce and up, but usually we use these lambda expressions, 05:13.920 --> 05:18.990 one lambda expressions which we create and then we use my producer for that on top of that. 05:19.260 --> 05:22.220 Now, let us understand what my producer enfolded is. 05:22.260 --> 05:25.300 So let us talk about math. 05:26.820 --> 05:37.920 OK, so what, Mark, does this map will simply try to map a function to when I tribal object. 05:38.400 --> 05:46.840 OK, so it will map a function to an eye, to the object. 05:47.340 --> 05:49.370 So this object could be a list. 05:49.380 --> 05:50.270 It could be a table. 05:50.280 --> 05:51.580 It could be anything. 05:52.320 --> 05:57.610 So it is not really considered, but it could be either a list or a dictionary or anything like that. 05:57.870 --> 06:00.200 So let's say we have a list in this case. 06:00.390 --> 06:02.430 So let us create a list. 06:03.460 --> 06:04.000 No. 06:06.030 --> 06:15.030 And let this list contain values one one one three, four, five, six, seven, eight, nine, and 06:15.450 --> 06:16.290 Graney five. 06:17.880 --> 06:19.020 Nine, twenty six minutes. 06:20.010 --> 06:22.800 And what I want to do is. 06:23.750 --> 06:25.400 I simply want to. 06:26.550 --> 06:33.930 Get these some of these values so I can get those also or what I want to get is instead of these values 06:33.930 --> 06:36.600 legacy, I just want to get something like. 06:37.530 --> 06:39.120 I want to simply get the. 06:40.300 --> 06:47.320 Squares of these values, let us say, I want to get these squares with these values so I can use map. 06:48.940 --> 06:57.430 And what I want to map, I need to give a function which I want to map, so let us say I have a function 06:57.790 --> 06:58.330 squit. 07:00.220 --> 07:08.770 OK, this is a function which basically runs the square of a number which I put in, and I want to map 07:08.770 --> 07:11.090 it to the numbers, the numbers which I have. 07:11.840 --> 07:15.370 OK, so I want to apply this on numbers. 07:16.060 --> 07:18.310 This is this infix of MUF. 07:19.540 --> 07:29.230 OK, what I can do is I can get the values using mapping this entire thing to a list so I can map this 07:29.230 --> 07:33.140 entire thing to a list and get these values as an output. 07:33.580 --> 07:37.470 So let us create a function square first. 07:37.720 --> 07:42.130 So this square function I want to generate using the expression. 07:42.610 --> 07:45.280 So instead of writing Square, what I can do is. 07:46.910 --> 07:48.410 I can simply say Lamda. 07:50.040 --> 07:53.300 And what do we give up, the land that we give the number? 07:53.400 --> 07:57.000 The argument which it needs to have, so let's say we want to give it. 07:59.630 --> 08:00.790 And what do you want to do? 08:00.820 --> 08:03.480 Do you want to get a squared off? 08:03.960 --> 08:08.150 OK, so we simply say do the power. 08:09.080 --> 08:12.310 So this will give the squared off as the result. 08:12.590 --> 08:15.380 And this is the function which we want to have. 08:15.390 --> 08:17.020 This is the function that you want to have. 08:17.240 --> 08:22.610 And this is the object on top of which we want to apply this function. 08:23.240 --> 08:26.600 OK, so what will happen when we run this? 08:32.320 --> 08:36.330 It is such a huge square, so let us have a smaller number here. 08:37.330 --> 08:38.890 There does have. 08:40.210 --> 08:45.520 A number like this, instead of giving aid to the power, we just need to give a square. 08:50.740 --> 08:52.550 OK, this is the square of the number. 08:53.620 --> 09:01.120 Now, if you're to a point now, see, what it does is it vibrates over the entire list. 09:01.360 --> 09:03.630 It has one, two, three, four, five, six, seven, eight. 09:04.240 --> 09:05.650 So it goes to one. 09:05.650 --> 09:06.550 It takes one. 09:07.210 --> 09:10.990 It finds out we need to do a square of it. 09:11.320 --> 09:17.560 And it then goes to the next number, finds a square and puts it next number, finds the square and 09:17.560 --> 09:18.610 makes no finds us. 09:19.140 --> 09:20.470 It does the entire thing. 09:21.670 --> 09:24.670 This is what we get from the map and. 09:26.550 --> 09:31.210 The list, which we have applied on top of it, converted into a list for. 09:32.340 --> 09:35.460 OK, so we can apply any kind of function here. 09:35.910 --> 09:41.370 OK, now let us say instead of this, what I want to do is I just want to have numbers. 09:41.790 --> 09:44.500 Let us do another trial on top of it. 09:44.700 --> 09:50.680 I want to get this number and I want to multiply some number with some other numbers. 09:50.680 --> 09:53.610 So let's say I have this number one. 09:53.790 --> 09:59.790 This is one list and I have another list of number two, which is the second number list, which I want 09:59.790 --> 10:00.150 to have. 10:00.480 --> 10:04.290 And I want to multiply this in the first list with the second list. 10:04.740 --> 10:08.700 And here I have nine numbers, so let's have another number. 10:10.140 --> 10:16.350 So I want to multiply this entire list with latency just then, but it could be any list of numbers. 10:22.800 --> 10:32.940 So this is three, this is three, and this is three, so now I instead of multiplying this with this, 10:32.940 --> 10:34.560 I want to multiply it with the. 10:35.860 --> 10:43.620 So I give me here and now this is the first argument, number one, and the second argument is number. 10:46.720 --> 10:53.860 So this is the function which I am want to map and what are the values which I want to map, which I 10:53.860 --> 10:56.230 want to map, number one. 10:57.550 --> 11:01.450 And number two, and what are these number one number? 11:01.870 --> 11:06.580 These are the values and we will be doing so if I run this. 11:07.680 --> 11:09.690 You get these values. 11:12.250 --> 11:19.120 So it just taking raising it to the public, if I do simple multiplication, get the isn't. 11:21.090 --> 11:24.450 So you can apply any kind of function using this map. 11:25.820 --> 11:28.170 This is what my function does. 11:29.110 --> 11:33.660 Now, let us try to understand what Filter does, OK? 11:34.890 --> 11:38.640 So let us go to filter. 11:40.680 --> 11:49.560 So the filter function returns and ideato OK, which yields the items of the approval for which the 11:49.560 --> 11:50.790 function is true. 11:51.270 --> 12:00.210 OK, so talking in the layman's language center will simply apply a filter on top of the object. 12:00.870 --> 12:02.430 OK, so let's see. 12:02.430 --> 12:04.960 I again have these numbers say no. 12:05.340 --> 12:07.150 OK, I have this number again. 12:08.450 --> 12:15.650 OK, I have these number one, so I want to apply for it so that it will give me not only the even values 12:15.650 --> 12:17.300 of only the old values. 12:17.570 --> 12:23.480 OK, so I can filter out these values and get only the values which I want out of this. 12:23.840 --> 12:25.220 This is what freedom does. 12:25.910 --> 12:28.310 OK, so what we can do is. 12:29.900 --> 12:31.670 We can simply create a function. 12:32.010 --> 12:37.460 OK, let us create a function which is checking if one number is even or not. 12:37.810 --> 12:41.720 OK, so let us define a function. 12:43.190 --> 12:43.580 Gay. 12:44.900 --> 12:45.730 Even our. 12:47.780 --> 12:50.480 And we are giving No. 12:52.300 --> 12:53.600 And what do we want to do? 12:55.060 --> 12:56.050 We want to do it on. 12:57.750 --> 12:59.700 If when the number is. 13:01.340 --> 13:04.490 Divided by two, is it zero or not? 13:04.700 --> 13:07.730 OK, if it is returning zero, that means it does. 13:07.730 --> 13:11.840 Even if it is not returning zero, then it means that this. 13:12.780 --> 13:16.020 Or so I'm giving it a zero. 13:16.950 --> 13:18.600 OK, now. 13:19.940 --> 13:20.900 We have this. 13:22.550 --> 13:28.310 On top of this now, I want to apply for you go on inside this building. 13:28.340 --> 13:34.670 Again, what I need to give is I want to give the function, but I want to use to feel that the. 13:36.500 --> 13:48.290 The will object, which I have, so I have this even I and I have this number is number one with me 13:49.220 --> 13:49.550 now. 13:49.550 --> 13:53.500 This even is not exactly a function. 13:53.660 --> 13:56.510 It is just a boolean expression, right? 13:56.720 --> 14:01.760 It is a boolean expression which will either give me a true or false kind of value. 14:01.940 --> 14:07.250 If the value is zero, it means that it is false if the value is other than zero. 14:08.260 --> 14:17.440 It means that it is true, so whatever value we have through it will simply mean that the expression 14:17.440 --> 14:20.980 is true and that particular value will come out of it. 14:21.190 --> 14:27.110 If the value is false, then the value will not be coming out of the fear that it will get filled up. 14:27.400 --> 14:33.060 It will just be struck that OK, so let us run this. 14:33.940 --> 14:35.730 So it gives me this filtered object. 14:36.130 --> 14:41.530 Now, what I can do is I can simply apply a list on top of it to get the values out of this. 14:44.070 --> 14:48.540 So when I done this, I get the even values. 14:49.890 --> 14:57.960 OK, so this is what my filter does now instead, if you don't really want to use this, even because 14:57.960 --> 15:01.070 we are using lambda functions, we want to use lambda functions. 15:01.290 --> 15:05.730 So what we can do is instead of writing this entire thing and writing the function and everything, 15:06.150 --> 15:09.740 we can simply do it this way. 15:10.140 --> 15:11.910 We can write the lambda function again. 15:12.990 --> 15:19.390 OK, the lambda function will take in value, so let us see it and we want to apply a function. 15:19.410 --> 15:20.820 So now we will check. 15:20.820 --> 15:26.850 If it is divided by two, then the remainder is equivalent to zero or not. 15:26.860 --> 15:31.850 So if the remainder is equal to zero, this function becomes true and gives the value up. 15:32.950 --> 15:37.330 So this is the same result using the lambda expression. 15:39.430 --> 15:47.170 OK, now let us try the next thing, which is the videos. 15:48.480 --> 15:49.020 So. 15:50.440 --> 15:52.390 What reduced does is. 15:55.320 --> 16:06.600 In case of produce, we will be able to retrieve some value, which is which is taken out from the continuous 16:06.900 --> 16:11.340 application of a function honor I object Your Honor sequence. 16:11.670 --> 16:13.580 So let me explain it to you. 16:14.100 --> 16:25.860 So let us talk about your news and we can use map for the LAMDA without any import. 16:26.100 --> 16:31.400 But when we are talking about produce, we need to import the photos. 16:31.650 --> 16:43.550 So the first thing which we need is import functor so we can import this as Ifti, OK. 16:44.100 --> 16:45.640 So this is one thing which we need. 16:45.990 --> 16:47.660 Now how the deals works. 16:48.000 --> 16:51.700 So let say I have a list of numbers, OK? 16:51.960 --> 16:53.430 I have a list of numbers. 16:53.430 --> 16:55.550 Say one comma. 16:55.650 --> 17:03.120 Forty six former twenty three comma twenty four comma nine comma eight from a five. 17:04.220 --> 17:10.950 Hundred one thousand eight, twenty three and two. 17:12.630 --> 17:19.380 OK, now, if I want to find out what is the maximum number out of this. 17:20.580 --> 17:22.230 Then how I can do it is. 17:23.590 --> 17:29.020 One thing is I can apply the maximum function, but this is not the purpose here, I want to explain 17:29.020 --> 17:29.990 how this works. 17:30.970 --> 17:38.050 So what we can do is what we will be doing is we will be out the first two numbers and we will compare. 17:38.740 --> 17:42.130 That is one greater or greater. 17:42.670 --> 17:44.330 Now, here we get 46. 17:44.620 --> 17:49.050 So 46 is the largest number out of these. 17:50.180 --> 17:51.500 So what we will have. 17:52.740 --> 17:53.670 We have this thing. 17:54.910 --> 18:03.480 So in the next libration, what I will have is I will have something like, I will have just six hours. 18:05.290 --> 18:09.430 Because this has again. 18:10.430 --> 18:10.910 Changed. 18:11.860 --> 18:16.390 OK, I will have this 46 now again, then I will be. 18:17.650 --> 18:26.020 Running this next iteration, so it will again go ahead and check if 46 is bigger or 23. 18:26.500 --> 18:31.950 Now, again, politics is bigger, so it will get rid of this 23 and we will have 46 in 10. 18:33.190 --> 18:35.220 Then again, it will keep going. 18:36.160 --> 18:39.250 And out of 46 and 34, it will give 46. 18:40.790 --> 18:42.590 So this is what we will have. 18:44.510 --> 18:51.740 Now, again, let's go to the next generation, so now it will compare what the six four nine, eight 18:51.740 --> 18:52.250 five. 18:52.490 --> 18:53.940 All of these will be compared. 18:54.500 --> 18:56.280 So it will keep only 46. 18:57.650 --> 19:00.830 Now, this would be like after several patients. 19:02.210 --> 19:08.840 Now, in the next iteration, what will happen is if will compare four to six and hundreds again now 19:08.900 --> 19:13.250 when it compares for the six, one hundred one hundred is again greater than four to six. 19:13.430 --> 19:23.240 So it will be a hundred and it will keep doing this entire thing until this entire list is reduced to 19:23.240 --> 19:24.440 just one number. 19:24.770 --> 19:27.790 And that one number will be outmuscled. 19:31.080 --> 19:33.870 This is what news is doing in. 19:34.860 --> 19:38.030 OK, so let's try to apply this to. 19:39.850 --> 19:43.810 OK, so let us have no. 19:45.500 --> 19:48.890 And let these be the values of No. 19:52.610 --> 19:59.510 And out of these numbers, what I want to do is I want to find out the max and what is Max Max's. 20:01.150 --> 20:03.430 F.T. Don't reduce. 20:04.400 --> 20:13.610 And what I want to do is I want to apply a lambda, I want to apply this lambda on equal, maybe there 20:13.640 --> 20:16.710 would be do values on which the expression would be applied. 20:17.030 --> 20:20.430 These two values will always be the force to values which we have. 20:20.690 --> 20:24.470 So in the first iteration, it will be one four forty six. 20:24.620 --> 20:31.130 In the next iteration it will be the result which will which we will get by applying the expression 20:31.130 --> 20:31.860 on these two. 20:32.240 --> 20:35.480 So we will get forty six out of this then it will apply. 20:36.550 --> 20:44.880 In the the expression on forty six and twenty three, then as a result we will get forty six, then 20:45.250 --> 20:53.680 applied on four to six and thirty four, then it will apply on forty six and nine, then it will again 20:53.680 --> 20:56.890 check with forty six and eight, then forty six and five. 20:57.190 --> 21:00.220 Then again it will take forty six and hundred. 21:00.550 --> 21:04.480 Then it will take between forty six and hundred. 21:04.480 --> 21:11.110 It will get one hundred as it is then it will take between hundred and one thousand and eight. 21:11.710 --> 21:14.900 So it will find over one thousand eight as that result. 21:15.370 --> 21:20.650 Then again it will take between one thousand eight hundred twenty three, it will get one thousand eight 21:20.650 --> 21:21.210 as a result. 21:21.400 --> 21:24.820 And then after comparing with two it will take one thousand eight. 21:25.480 --> 21:29.050 So this is the entire thing which we will be which will be going on internally. 21:29.470 --> 21:31.240 So it will do this. 21:32.910 --> 21:34.650 And what it will do. 21:36.000 --> 21:36.960 It will be done. 21:44.350 --> 21:46.390 It is great than then be. 21:49.800 --> 21:51.590 Ends it with. 21:52.590 --> 21:53.560 Summerton v.. 21:55.300 --> 21:57.460 And it will run this entire thing. 21:58.510 --> 22:00.070 Poll numbers. 22:01.440 --> 22:04.320 OK, now let us run, Max. 22:06.480 --> 22:09.120 So we get one thousand eight as it is in. 22:10.900 --> 22:19.410 OK, now let's say we want to calculate some numbers from C one, two hundred, we can apply this again, 22:19.900 --> 22:21.940 so let us see some. 22:25.990 --> 22:28.720 Although if not reduce. 22:29.850 --> 22:35.640 And what we want to do, we want to apply lamda, what is the lamda function doing? 22:35.970 --> 22:43.500 It is adding e it is getting the value equal maybe, and it is doing a Lusby. 22:44.850 --> 22:46.350 And it is doing this on. 22:48.110 --> 22:52.030 Numbs our let us see range. 22:54.080 --> 22:57.350 One to one hundred and one. 22:59.300 --> 23:08.370 And let us Lonesome's so here we get some of numbers from one to one hundred and one. 23:08.960 --> 23:10.790 Similarly, we could do anything like that. 23:10.800 --> 23:13.430 We can maybe multiply these numbers. 23:14.240 --> 23:16.260 We get something like that again. 23:16.290 --> 23:20.180 And this we get this so you can apply any function. 23:20.330 --> 23:27.560 But just need to remember how the deals works, how my books, how filter works. 23:27.710 --> 23:32.110 So just to reiterate the entire thing, because it is a little complex in nature. 23:33.570 --> 23:41.430 Map will apply this function on top of the list, which we will be providing, we can provide multiple 23:41.430 --> 23:47.920 lists and these lists will correspond to each and every variable which you will be having. 23:48.150 --> 23:53.910 So here no one will correspond to a number, will correspond to me. 23:54.120 --> 23:55.290 So it gives me hives. 23:55.290 --> 24:02.010 See, also then we can give any other list also as names to be anything like that could be done. 24:02.670 --> 24:07.680 So there is no specific restriction on how many variables you need to have in your lambda expression. 24:09.020 --> 24:16.160 My function will just apply a function on all the elements of the iterable object. 24:17.290 --> 24:19.360 Fater will apply. 24:20.700 --> 24:26.840 Expression, alumni expression, which will be giving a boolean value or. 24:27.940 --> 24:34.180 Numeric value as a design, which will be if it is zero, it will mean that it is false. 24:34.190 --> 24:40.260 If it is non-zero, it will mean that it is true and for whatever value for which the desired of the 24:40.600 --> 24:45.070 expression is coming through, that will be given out as a. 24:47.580 --> 24:54.660 And what reduced does this reduce will loop over the entire apremilast? 24:56.710 --> 25:04.750 With a set of two values, so it will run on the top of these two and produce these two values into 25:04.750 --> 25:08.920 one value, then pick out the next value and. 25:10.210 --> 25:11.740 Keep on doing the entire thing. 25:12.070 --> 25:20.440 It has introduced the entire iterable list in just one single value, and that value comes out as the 25:20.440 --> 25:25.770 deciding this is what my produce folder is and this is how we use it. 25:27.310 --> 25:31.360 You can try different things, you can try different. 25:33.650 --> 25:41.630 Samples for this, you can try different ways for this, you can apply different expressions and triangulate 25:41.630 --> 25:42.970 on how this works.