WEBVTT 0 00:00.170 --> 00:06.560 So the code challenge that you're about to do comes from a really interesting phenomenon that you might 1 00:06.560 --> 00:08.120 find in London. 2 00:08.150 --> 00:13.850 I live in London and it's well known as a big financial district. 3 00:13.850 --> 00:20.810 So when you head over to the city or the financial area in London and you go into a restaurant, 4 00:20.810 --> 00:23.510 you might see a strange thing happen. 5 00:23.510 --> 00:29.830 You might see a whole bunch of people in suits who look very much like the financial banker types. 6 00:30.310 --> 00:35.260 At the time when they actually need to pay the bill, you see everybody pull out their business 7 00:35.260 --> 00:37.780 cards and put it into a bowl. 8 00:37.930 --> 00:40.090 So what's actually going on here? 9 00:40.120 --> 00:47.020 A friend of mine told me, apparently there's this game that the rich banker types play where 10 00:47.020 --> 00:50.110 it's kind of like Russian roulette with the bill. 11 00:50.110 --> 00:56.290 So everybody puts their business card in, and the person's card who gets picked out has to pay for 12 00:56.290 --> 00:59.440 everybody's bill, which is kind of crazy, 13 00:59.440 --> 01:01.150 but then again, it's finance. [Music sound by Megan Boni plays] 14 01:01.240 --> 01:04.990 "...finance with a trust fund, 6'5”, blue eyes.” [Music ends] 15 01:04.990 --> 01:05.740 But you know what? 16 01:05.740 --> 01:11.140 We don't need anybody in finance because we are programmers and we can do everything they can do just 17 01:11.140 --> 01:12.130 by writing code. 18 01:12.130 --> 01:13.840 So here's the challenge, 19 01:13.840 --> 01:21.630 you are to look through this friends list and you're going to write some code using what you've learned 20 01:21.630 --> 01:30.060 about randomization in Python, and also lists in Python to be able to print out a random, one of these 21 01:30.060 --> 01:30.870 names. 22 01:30.870 --> 01:35.610 So each time you run the code, it will print out a different name. 23 01:35.610 --> 01:43.470 So if I run the solution file, you can see that each time it prints out a different random name from 24 01:43.470 --> 01:45.710 this list of friends. 25 01:46.340 --> 01:49.970 So think about how you might solve this challenge. 26 01:49.970 --> 01:57.710 You can look through the list of hints in the description box here, but think back to what you've learned 27 01:57.710 --> 02:01.790 in today's lessons and see if you can solve this challenge. 28 02:01.820 --> 02:03.020 Pause the video now. 29 02:05.240 --> 02:05.840 All right. 30 02:05.840 --> 02:14.230 So what we want to do is to be able to tap into this list and get hold of a random item. 31 02:14.350 --> 02:16.990 Now there's two ways of doing this. 32 02:16.990 --> 02:20.290 And it depends on which path you went down. 33 02:20.290 --> 02:27.670 So let's go through the first way, which is maybe you thought let's go through the documentation. 34 02:28.300 --> 02:36.430 So if you look through the random documentation which we saw earlier in today's lessons, you might 35 02:36.430 --> 02:42.130 scroll through all of this and think, hmm, there must be a way that Python has created for us to be 36 02:42.130 --> 02:45.880 able to randomly get items from lists. 37 02:45.910 --> 02:49.150 Now, it's not easy to find, but there is one, 38 02:49.150 --> 02:51.340 it's random.choice() . 39 02:51.370 --> 02:59.820 Now, another way you might have arrived at this is simply using the Google search and saying, "get 40 02:59.820 --> 03:04.980 random item from list..." and then adding the word "Python" at the end. 41 03:05.100 --> 03:10.740 And you might look through StackOverflow and you might come across the same function. 42 03:10.740 --> 03:15.600 Then you can go in the documentation and see how it works and to read about it. 43 03:15.600 --> 03:18.630 So this is probably the simplest way to do it. 44 03:18.630 --> 03:28.280 And we can simply print(random...) Now, in order to use this module, you can see we need to use the import 45 03:28.280 --> 03:29.180 statement, 46 03:29.180 --> 03:31.850 otherwise it doesn't know what random is. 47 03:31.850 --> 03:34.610 So let's import random first, 48 03:34.610 --> 03:36.350 and you can see that error goes away. 49 03:36.350 --> 03:41.720 And then within the Random Module, I'm going to use the choice() function. 50 03:41.720 --> 03:46.220 And this function takes as its input a sequence. 51 03:46.220 --> 03:53.320 Now the list is one such type of sequences in Python, and there are others which we will learn about 52 03:53.320 --> 03:54.700 in later lessons. 53 03:54.700 --> 04:02.350 But this is all that it takes to go ahead and pick out a random name from this list. 54 04:02.380 --> 04:06.190 Now this is option number one, 55 04:07.810 --> 04:14.680 and this is something that you might have thought of based on, you know, thinking about 56 04:14.680 --> 04:18.430 documentation and thinking about how we can find out things from the internet, 57 04:18.430 --> 04:21.040 and this is a really, really key skill of programmers. 58 04:21.040 --> 04:27.340 But the other key skill is figuring out how to do something based on what we already know how to do. 59 04:27.370 --> 04:36.730 So the second option is to use what we already know, which is we know that we can use random.randint() 60 04:36.730 --> 04:42.270 to get a random integer, and we can set the range of random numbers. 61 04:42.270 --> 04:45.330 So we know that lists start counting from 0, 62 04:45.330 --> 04:47.820 so Alice is at index 0. 63 04:47.820 --> 04:54.420 So we would need random numbers between 0, 1, 2, 3, and 4. 64 04:54.420 --> 05:02.310 So if we do randint(0, 4), then we will get a random number anywhere between 0 and 4 including 0 65 05:02.310 --> 05:03.020 and 4. 66 05:03.050 --> 05:12.860 Now if this is our random_index, then we can use this random_index to print out a random name from 67 05:12.860 --> 05:13.700 the friends list. 68 05:13.700 --> 05:20.690 So remember we can tap into a list, add a set of square brackets, and then put in an index 69 05:20.690 --> 05:22.970 to fetch an item from that list. 70 05:22.970 --> 05:30.790 So if I go ahead and run this file, you'll see that the first name comes from the first random.choice(), 71 05:30.790 --> 05:34.420 and the second one comes from using the random_index. 72 05:34.420 --> 05:36.940 And you can see that they're both random, 73 05:36.940 --> 05:41.110 and they both go through our list, and they both do exactly the same function. 74 05:41.110 --> 05:47.200 And if you picked option one or if you picked option two, it's totally the same. 75 05:47.200 --> 05:50.830 It's up to you how you decided to complete this challenge, 76 05:50.830 --> 05:53.440 both ways are equally valid. 77 05:53.470 --> 05:59.080 Now, in reality, if you know that there is something called random.choice(), you would probably go 78 05:59.080 --> 06:03.160 for this because it's less code and it's pretty readable, 79 06:03.160 --> 06:05.890 random.choice() from this list, 80 06:05.890 --> 06:09.220 but the second option is also equally valid. 81 06:09.220 --> 06:14.740 So if you didn't manage to complete the challenge, or if you had any bugs in your code, go back and 82 06:14.740 --> 06:15.190 fix that. 83 06:15.400 --> 06:17.920 Otherwise, I'll see you in the next lesson.