1 00:00:00,360 --> 00:00:03,330 Now, our next challenge is our press up. 2 00:00:04,170 --> 00:00:09,170 And this challenge is going to require you to draw a random walk. 3 00:00:10,080 --> 00:00:14,850 Well, it's basically your turtle making random movements North, East, 4 00:00:14,850 --> 00:00:19,620 South, or West, each time it progresses by the same distance, 5 00:00:19,950 --> 00:00:24,810 but it can at any point choose which direction it wants to go out of the four. 6 00:00:25,290 --> 00:00:29,130 And also you can see we've kept the color palette from the previous challenge, 7 00:00:29,460 --> 00:00:34,410 and I've just applied it to the random walk so that each time it walks, 8 00:00:34,470 --> 00:00:36,090 it's going to pick a different color. 9 00:00:37,110 --> 00:00:42,110 Now this random walk is something that's used often in mathematics and other 10 00:00:42,630 --> 00:00:43,463 disciplines. 11 00:00:43,650 --> 00:00:48,650 So it's a way that can be used to model various real life situations. 12 00:00:49,380 --> 00:00:50,700 Like for example 13 00:00:50,700 --> 00:00:55,700 the financial status of a gambler or things like the path of a molecule in a 14 00:00:57,270 --> 00:01:01,320 liquid or gas or the search path of a foraging animal, 15 00:01:01,380 --> 00:01:06,000 and a whole bunch of other things. Take a look at this Wikipedia article 16 00:01:06,030 --> 00:01:09,600 which I'll link to and take a look at all the applications 17 00:01:09,630 --> 00:01:14,630 including sculpture making or Physics or brain research and a whole lot more. 18 00:01:16,560 --> 00:01:17,820 So once you're ready, 19 00:01:18,030 --> 00:01:23,030 go ahead and see if you can program your turtle to create a random walk using 20 00:01:23,310 --> 00:01:24,210 random colors. 21 00:01:24,480 --> 00:01:29,480 And I want you to think about how you can get the thickness of the drawing seen 22 00:01:30,180 --> 00:01:33,600 here, so each of the lines is a lot thicker than before. 23 00:01:34,140 --> 00:01:39,140 And also see if you can figure out how you can speed up the turtle so that it 24 00:01:39,330 --> 00:01:43,050 draws much faster. And everything is of course 25 00:01:43,050 --> 00:01:47,430 going to be in the documentation somewhere for you to find. Pause the video and 26 00:01:47,430 --> 00:01:48,660 complete the challenge now. 27 00:01:52,820 --> 00:01:56,240 Alright. So I'm going to delete all the code from our previous challenge, 28 00:01:56,510 --> 00:01:59,150 but I'm going to keep my list of random colors, 29 00:01:59,450 --> 00:02:01,610 which I'm going to use for my random walk here. 30 00:02:02,510 --> 00:02:04,370 Now I'm going to keep the random import 31 00:02:04,400 --> 00:02:08,180 even though it's currently unused because, as you guessed it, our random 32 00:02:08,190 --> 00:02:10,759 walk is going to require some randomness. 33 00:02:11,780 --> 00:02:16,640 So how do we actually get our robot to move in the four different directions? 34 00:02:17,090 --> 00:02:20,240 Well, let's define another list called directions 35 00:02:20,750 --> 00:02:24,560 and this is going to have all of the different directions 36 00:02:24,590 --> 00:02:27,800 the turtle can face. So we'll start from 0 37 00:02:28,190 --> 00:02:32,240 which will be facing East and then 90, 38 00:02:32,240 --> 00:02:37,240 which will be facing North, 180 will be West and 270 will be South. 39 00:02:40,220 --> 00:02:42,800 So now that we've got these random directions, 40 00:02:42,830 --> 00:02:46,160 we can get Tim, our little turtle, to start moving. 41 00:02:46,610 --> 00:02:49,940 So every time we're going to move forward by the same distance, 42 00:02:50,630 --> 00:02:53,360 and it doesn't really matter how far you move your turtle 43 00:02:53,780 --> 00:02:56,480 as long as you set a reasonable number. 44 00:02:56,750 --> 00:03:01,750 So I'm just going to choose 30 and then I'm going to get my turtle to turn in a 45 00:03:02,560 --> 00:03:03,820 random direction. 46 00:03:04,330 --> 00:03:09,330 So I don't want to just use right all the time, so you can use left or right, 47 00:03:10,390 --> 00:03:14,710 and pick a random direction from the list. But alternatively, 48 00:03:14,710 --> 00:03:18,490 you can actually use this set heading. So for example, 49 00:03:18,520 --> 00:03:21,100 we can set it to those four directions. 50 00:03:21,640 --> 00:03:26,560 All we have to do is call setheading and then pass in one of those angles. 51 00:03:27,250 --> 00:03:28,210 That's what we're going to do here. 52 00:03:28,240 --> 00:03:33,240 We're going to use the random module and the random choice method to pick a 53 00:03:34,900 --> 00:03:36,340 random direction. 54 00:03:37,660 --> 00:03:42,660 So now this robot is going to move forwards and then it's going to turn a random 55 00:03:43,420 --> 00:03:47,230 direction. But of course, we want this to loop a few times. 56 00:03:47,320 --> 00:03:50,350 So let's say that we get it to loop 200 times. 57 00:03:50,410 --> 00:03:53,740 I think that should be enough to draw a decent sized image. 58 00:03:54,400 --> 00:03:58,600 Let's set the range to maybe 200 times for this loop to run. 59 00:03:58,930 --> 00:04:01,480 I think that should get us a decent image. Now, 60 00:04:01,480 --> 00:04:05,770 if you chose 300 or 500 or whatever the number, it doesn't matter. 61 00:04:06,190 --> 00:04:10,240 As long as you can get a decent image on screen, then it's perfectly fine. 62 00:04:10,960 --> 00:04:14,170 So we've now satisfied the basic constraints of a random walk 63 00:04:14,350 --> 00:04:18,130 and you can see our turtle is now wandering around this alleyway, 64 00:04:18,160 --> 00:04:21,820 completely aimlessly and modeling a real life process, 65 00:04:21,880 --> 00:04:23,650 like an animal that's hunting for food. 66 00:04:25,120 --> 00:04:27,370 Now let's implement the next part of this. 67 00:04:27,490 --> 00:04:32,490 Let's go ahead and change our code so that it generates a random color for each 68 00:04:32,560 --> 00:04:33,393 step. 69 00:04:33,850 --> 00:04:37,870 That's pretty simple cause we did it before in the last lesson. 70 00:04:38,200 --> 00:04:42,640 So we're going to get Tim to change his color and we're going to use the random 71 00:04:42,640 --> 00:04:43,473 module 72 00:04:45,100 --> 00:04:50,100 and the choice method to pick from all the colors that we've already got in this 73 00:04:50,800 --> 00:04:55,390 list here. Now that it's pretty much random colors, 74 00:04:55,540 --> 00:04:58,510 random walking, the next thing we want to do 75 00:04:58,780 --> 00:05:03,780 if you saw my demo of it is we want to make each of the lines a bit thicker. 76 00:05:04,570 --> 00:05:09,040 So how do we do that? Well, we have to head back to the documentation. 77 00:05:09,670 --> 00:05:12,370 So it's probably going to be one of these methods. 78 00:05:12,760 --> 00:05:15,100 And if we just read through the names of the methods, 79 00:05:15,400 --> 00:05:20,400 they should give us a bit of an indication of which one might be the one that we 80 00:05:20,680 --> 00:05:21,513 want. 81 00:05:22,540 --> 00:05:26,020 If we take a look at the drawing control for our pen, 82 00:05:26,290 --> 00:05:31,290 you can see there's a method called pen size and you can call this either pen 83 00:05:31,480 --> 00:05:35,350 size or width, but it does the same thing. Essentially 84 00:05:35,350 --> 00:05:39,130 it just sets the size of the pen which the turtle draws with. 85 00:05:40,900 --> 00:05:45,070 If we set the pen size to something a little bit wider, 86 00:05:47,380 --> 00:05:50,710 say maybe 15 in width, 87 00:05:51,370 --> 00:05:53,830 then you can see when our turtle draws, 88 00:05:53,890 --> 00:05:57,130 it's now a lot wider and it's a lot easier to 89 00:05:57,260 --> 00:05:59,420 see what it's doing. Now, 90 00:05:59,420 --> 00:06:03,290 the final trick I want to show you is how you can speed up the turtle's 91 00:06:03,290 --> 00:06:07,100 animation. So if I was to wait for it to finish drawing here, 92 00:06:07,100 --> 00:06:08,630 that's perfectly possible, 93 00:06:08,840 --> 00:06:13,840 but I can also speed it up by tapping into the speed method for turtle. 94 00:06:15,020 --> 00:06:20,020 And I can either specify this speed as an integer or as a string. 95 00:06:22,070 --> 00:06:25,940 So the strings are fastest, fast, normal, slow, slowest, 96 00:06:26,240 --> 00:06:30,950 and this determines the animation speed of the turtle as it draws. 97 00:06:31,370 --> 00:06:35,900 So I'm going to go for fastest so we can say tim. 98 00:06:35,900 --> 00:06:40,340 speed. And we'll put in that string, fastest. 99 00:06:41,480 --> 00:06:46,040 And now when we run it, you can see it animates way faster 100 00:06:46,400 --> 00:06:48,500 and it's drawing at the speed of light. 101 00:06:49,070 --> 00:06:52,580 Our little turtle is completely going nuts, 102 00:06:53,780 --> 00:06:58,610 but this means that it will take much less time to complete our 200 cycles as 103 00:06:58,630 --> 00:06:59,620 we requested. 104 00:07:00,970 --> 00:07:04,870 So I hope you enjoyed this lesson and you managed to get your turtle to do a random 105 00:07:04,870 --> 00:07:06,130 walk. Now, 106 00:07:06,250 --> 00:07:09,760 many of you would have done this challenge and you might've thought, wouldn't it 107 00:07:09,760 --> 00:07:14,760 be nice if I could generate a completely random color rather than just selecting 108 00:07:15,070 --> 00:07:17,800 a random one from this list? Well, 109 00:07:17,920 --> 00:07:21,520 we can do that and I'll show you how in the next lesson.