WEBVTT 00:00.400 --> 00:05.470 In previous lectures, you learned how to access a single element in a list, and in this section you 00:05.470 --> 00:08.710 will learning how to walk through all the elements in a list. 00:08.710 --> 00:14.380 So you can also work with a specific group of items in a list called a slice in Python. 00:14.380 --> 00:20.410 So to make a slice, you specify the index of the first and last elements you want to work with. 00:20.500 --> 00:26.860 As with the range function, Python stops one item before the second index. 00:26.860 --> 00:34.540 You specify the output of the first three elements in a list you will request here indicates root zero. 00:35.560 --> 00:36.160 To. 00:37.300 --> 00:38.080 Three here. 00:38.860 --> 00:48.310 So now if you write 033023 here, we will get this here and this is our slice. 00:48.550 --> 00:51.340 So here I will create some examples here. 00:51.340 --> 01:00.670 So let's again make some example about car makers or let's sometime now, Yeah, car makers is okay. 01:01.060 --> 01:06.760 Car makers here we will add BMW, Honda here. 01:07.570 --> 01:09.820 We will add Volkswagen. 01:11.070 --> 01:13.080 We will add the fourth. 01:14.380 --> 01:15.090 And I. 01:17.400 --> 01:18.000 Here. 01:19.020 --> 01:20.520 And this sun here. 01:20.520 --> 01:26.450 So here we will print print the zero three. 01:26.460 --> 01:29.550 So print carmakers. 01:31.020 --> 01:33.240 Carmakers zero three here. 01:33.540 --> 01:41.760 So this code now, let this code prints a slice of the list so the output retains the structure of a 01:41.790 --> 01:47.040 list and includes the first three carmakers in the list here. 01:47.040 --> 01:50.490 So in this case, it's going to print us here. 01:51.220 --> 01:58.510 It's going to print us BMW, Honda, BMW, Honda and Volkswagen. 01:58.660 --> 02:03.970 So it will print us these three items as we write in zero and three here. 02:04.600 --> 02:05.950 So now let's print this. 02:05.950 --> 02:08.800 And as you can see here, BMW, Honda, Volkswagen. 02:08.800 --> 02:12.100 So you can generate any subset of a list. 02:12.250 --> 02:22.120 For example, if you want to if you want to if you want to second and second, third and fourth item 02:22.120 --> 02:24.040 in a list, you will do this. 02:25.250 --> 02:25.580 Here. 02:25.580 --> 02:30.560 As you can see here, we started Honda, Volkswagen and Ford. 02:32.840 --> 02:36.140 And this time the slides start. 02:36.380 --> 02:40.900 Start with Honda here and ends with the Ford. 02:40.910 --> 02:46.970 So if you omit the first index and a slice Python automatically starts your slice at the beginning of 02:46.970 --> 02:47.930 the list. 02:47.960 --> 02:49.460 Like this here. 02:50.790 --> 02:52.680 You just need to add this double dot here. 02:52.680 --> 02:58.560 And as you can see here, we got BMW, Honda, Volkswagen and Ford. 03:00.800 --> 03:01.700 So. 03:02.450 --> 03:07.250 So a similar syntax works if you want to slice that includes the end of a list. 03:07.280 --> 03:14.900 So for example, if you want to, um, all items from the third item through the last item, you can 03:14.900 --> 03:23.390 do this two double dot, but this double dot here will have, will, will come after the number to get 03:23.390 --> 03:25.510 the last item. 03:25.520 --> 03:27.950 So here we get from the last item. 03:27.950 --> 03:34.130 Now in this case, we will get, as you can see here, let's actually. 03:35.410 --> 03:36.410 Where is my marker? 03:36.410 --> 03:37.060 Yes. 03:37.070 --> 03:40.010 So here we got Nissan. 03:40.990 --> 03:41.410 Kia. 03:42.220 --> 03:42.670 Hyundai. 03:45.650 --> 03:46.730 Volkswagen. 03:47.460 --> 03:48.540 And that's it. 03:49.360 --> 03:53.470 We got from here to here. 03:53.470 --> 03:55.840 So we got to here. 03:56.010 --> 03:58.300 We counted zero one second. 03:58.300 --> 04:03.340 And from second we told Python that get all those items from the list. 04:03.900 --> 04:04.720 So. 04:06.070 --> 04:12.250 Now Python returns all the items from the third item that through the end of the list. 04:13.510 --> 04:15.550 So I can afford and Nissan. 04:15.850 --> 04:21.340 So this syntax allows you to output all the elements from any point in your list to the end, regardless 04:21.340 --> 04:23.620 of the length of the list or something. 04:23.620 --> 04:31.000 So recall that a negative index returns an element a certain distance from the end of a list. 04:31.030 --> 04:34.660 Therefore, you can output any size of the end of a list. 04:34.690 --> 04:45.730 For example, if you want to output the last three carmakers on the carmakers, we can use this slice 04:45.910 --> 04:46.990 like this here. 04:49.490 --> 04:54.050 Minus three, negative three here and this double dot here and after that. 04:57.330 --> 04:58.590 We will print this. 04:58.950 --> 05:04.350 And as you can see here, we printed Hyundai, Kia, Nissan here. 05:04.800 --> 05:09.870 So you can actually include the third value in the braces indicating a slice. 05:09.870 --> 05:18.960 So if a third value is included, the test Python, how many items to skip between items in the specified 05:18.960 --> 05:19.550 range. 05:19.560 --> 05:26.280 So you can use a slice in a for loop if you want to loop through the subset of the elements in a list. 05:26.280 --> 05:35.130 So in this example, we will loop through the first three car makers and print their names as a part 05:35.130 --> 05:36.300 of a simple car maker. 05:36.660 --> 05:44.550 Now we will print here, here, here are the first. 05:47.690 --> 05:49.460 First for. 05:51.960 --> 05:55.770 For car makers in my list here. 05:55.770 --> 06:00.780 And after that we will use for loop for car maker. 06:00.810 --> 06:04.080 Car maker in car makers. 06:04.080 --> 06:06.690 And here we will enter this. 06:12.060 --> 06:12.870 Here for. 06:12.870 --> 06:16.470 And after that, we will play print here. 06:17.380 --> 06:22.660 Well print the carmaker dot title. 06:24.450 --> 06:26.160 So here we will. 06:26.460 --> 06:27.000 Let's run this. 06:27.000 --> 06:30.270 And as you can see here, we got this example, We got this output. 06:30.270 --> 06:36.960 So instead of looping through the entire list of players or car makers, Python loops through only the 06:36.960 --> 06:40.620 first three first for car makers. 06:40.620 --> 06:43.680 So slices are very useful in a number of situations. 06:43.680 --> 06:51.240 For instance, when you are creating a game, you could add a player, you could add a car makers model 06:51.270 --> 06:52.200 to a list. 06:52.200 --> 06:58.230 Every time that that car is running or playing, the player is playing with that car. 06:58.230 --> 07:00.360 So you could then get a player's. 07:01.290 --> 07:09.300 Top three scores by sorting the list in decreasing order and taking a slice that includes just the first 07:09.300 --> 07:11.130 three scores.