1 00:00:00,420 --> 00:00:04,110 First, let's start by improving our snake game, 2 00:00:04,650 --> 00:00:09,150 getting it to be able to keep track of the high score that we attain each time 3 00:00:09,150 --> 00:00:14,150 we play the game so that we can see what our high score is and keep striving to 4 00:00:14,310 --> 00:00:15,150 better ourselves. 5 00:00:16,200 --> 00:00:21,180 Open up the snake game in PyCharm that you created a few days back. Now, 6 00:00:21,180 --> 00:00:23,430 if you can't find your snake game project, 7 00:00:23,820 --> 00:00:28,170 or if you've made some significant changes to it where it might be confusing to 8 00:00:28,170 --> 00:00:32,490 follow along with the tutorial, then simply just head over to this URL 9 00:00:32,670 --> 00:00:34,770 which is in the course resources 10 00:00:35,220 --> 00:00:39,980 and then you can go ahead and hit download as a zip, unzip 11 00:00:39,980 --> 00:00:43,470 the downloaded file, and then open it inside PyCharm 12 00:00:43,860 --> 00:00:47,190 and you should end up with the same project as I have here. 13 00:00:47,940 --> 00:00:49,260 And once you've done that, 14 00:00:49,410 --> 00:00:53,880 then we can begin to start adding the functionality to keep track of the high 15 00:00:53,880 --> 00:00:57,060 score. Firstly, I'm going to add 16 00:00:57,060 --> 00:01:01,410 another attribute to my scoreboard, which is going to be called high_score. 17 00:01:01,920 --> 00:01:06,060 And again, it's going to start out as zero. Now, 18 00:01:06,090 --> 00:01:11,090 the next thing I'm going to do is I'm going to replace this game over method 19 00:01:11,910 --> 00:01:16,680 with a new method. We're not going to stop the game and write game over anymore. 20 00:01:17,130 --> 00:01:19,770 Instead, we're going to reset the scoreboard. 21 00:01:20,430 --> 00:01:23,730 So what happens when we reset the scoreboard? Well, 22 00:01:23,730 --> 00:01:28,730 we need to figure out if the current score that the user has attained is greater 23 00:01:29,640 --> 00:01:34,170 than the high score of all time. And if that is the case, 24 00:01:34,260 --> 00:01:38,850 then we're going to update the high score with the value of the current score. 25 00:01:39,420 --> 00:01:42,150 So the code for that would look something like this. 26 00:01:42,540 --> 00:01:47,250 If self.score is greater than self.high_score, 27 00:01:47,670 --> 00:01:52,670 well in that case then self.high_score is going to be equal to self.score. 28 00:01:53,910 --> 00:01:56,400 Now, this looks a little bit confusing at first, 29 00:01:56,730 --> 00:02:00,780 but if you just go through the logic and think about how you would create a high 30 00:02:00,780 --> 00:02:02,250 score saving mechanism, 31 00:02:02,700 --> 00:02:07,290 then you'll pretty quickly understand what's going on here. Now, 32 00:02:07,290 --> 00:02:12,270 once we've updated the high score, the next thing to do is to reset the score. 33 00:02:12,690 --> 00:02:17,340 So I'm going to reset it down to zero. Now, remember the order of your code 34 00:02:17,340 --> 00:02:21,780 matters a huge deal because if you first set the score to zero, 35 00:02:22,050 --> 00:02:25,350 then it's never going to be greater than the current high score. 36 00:02:25,560 --> 00:02:27,450 So this will never get triggered. 37 00:02:27,870 --> 00:02:32,550 So as always, be careful where you're writing your code. Now, 38 00:02:32,640 --> 00:02:36,990 after we've set the score, then we need to update the scoreboard. 39 00:02:37,740 --> 00:02:38,010 Now, 40 00:02:38,010 --> 00:02:42,870 one thing that I've changed about the scoreboard is previously when we increased 41 00:02:42,930 --> 00:02:43,950 the score, 42 00:02:44,340 --> 00:02:48,780 I've used the self.clear and then self.update_scoreboard. 43 00:02:49,230 --> 00:02:52,350 But it actually makes more sense for this clear to happen 44 00:02:52,380 --> 00:02:54,780 every single time we update the scoreboard. 45 00:02:55,230 --> 00:02:59,010 So I've added this method call here before we actually write the score. 46 00:03:00,160 --> 00:03:04,330 The reason why I couldn't do this previously is because when we wanted to show 47 00:03:04,330 --> 00:03:05,200 game over, 48 00:03:05,620 --> 00:03:10,000 we wanted to keep the score on the screen and then for 49 00:03:10,000 --> 00:03:15,000 the score board turtle to go to the center and write game over so that both of 50 00:03:15,280 --> 00:03:17,080 these things show up on screen. 51 00:03:17,740 --> 00:03:20,680 But now that we're getting rid of our game over method, 52 00:03:21,130 --> 00:03:26,130 then we can go ahead and move that clear to update scoreboard 53 00:03:26,590 --> 00:03:30,400 and then we don't have to call it twice, both in reset and increase_score. 54 00:03:31,390 --> 00:03:34,600 Now, in addition to writing the score, 55 00:03:34,900 --> 00:03:37,330 I'm now also going to write the high score, 56 00:03:37,960 --> 00:03:42,490 and this is going to be using an f-string to insert self.high_score. 57 00:03:43,420 --> 00:03:45,910 Now, if we run this game as it is, 58 00:03:45,970 --> 00:03:48,580 you can see it says score 0, high score 59 00:03:48,580 --> 00:03:51,430 0 using these initial values. 60 00:03:52,180 --> 00:03:54,550 But as soon as it hits the wall, 61 00:03:54,580 --> 00:03:57,430 it ends because in our main.py 62 00:03:57,760 --> 00:04:02,760 we change this game_is_on to false and that ends our while loop. 63 00:04:04,060 --> 00:04:04,840 Instead, 64 00:04:04,840 --> 00:04:09,840 what I'm going to do is I'm going to delete this game_is_on equals false and 65 00:04:10,660 --> 00:04:13,390 also delete it when we collide with the tail. 66 00:04:14,020 --> 00:04:18,250 And I'm also going to delete the part where we call game over from the score 67 00:04:18,250 --> 00:04:23,020 board. Instead, I'm going to get the scoreboard to reset itself. 68 00:04:24,490 --> 00:04:29,490 So that way the score gets reset to zero and we're ready with the next round. 69 00:04:30,730 --> 00:04:35,080 So now if I run this game again, you can see it says, score is 0, 70 00:04:35,380 --> 00:04:40,000 and then as soon as we get a higher score and we end up dying, like 71 00:04:40,000 --> 00:04:43,930 so, then our high score goes to 2. 72 00:04:44,560 --> 00:04:49,560 But our snake kind of just disappears because it continues moving in the same 73 00:04:50,560 --> 00:04:54,850 direction and it's now probably somewhere, all the way down to the left. 74 00:04:55,420 --> 00:05:00,100 What we do instead? Well, our snake also needs to be reset. 75 00:05:00,610 --> 00:05:04,990 So let's create a reset method inside the snake class as well. 76 00:05:05,680 --> 00:05:10,680 And all we're going to do is we're going to get all of the segments to clear. 77 00:05:11,770 --> 00:05:13,510 And when I hover over this clear, 78 00:05:13,510 --> 00:05:18,510 you can see what it does is it's going to remove all of the items from that 79 00:05:18,760 --> 00:05:19,360 list. 80 00:05:19,360 --> 00:05:24,360 So all of the segments that we've added already to the list of segments is 81 00:05:24,490 --> 00:05:28,780 going to be deleted. And then once we've gotten rid of all the segments, 82 00:05:28,810 --> 00:05:31,540 we're going to call self.create_snake again, 83 00:05:31,810 --> 00:05:36,490 so that we create another three-segment snake in the starting position. 84 00:05:37,660 --> 00:05:38,650 Now, in addition, 85 00:05:38,680 --> 00:05:43,680 I'm also going to set the self.head as the zeroth element from that list 86 00:05:44,920 --> 00:05:45,753 of segments. 87 00:05:46,150 --> 00:05:50,620 So basically we're doing everything that is in the init because we're going to 88 00:05:50,620 --> 00:05:53,620 initialize the snake again, back at the center. 89 00:05:54,220 --> 00:05:59,120 So now if I go back to main.py, and in addition to resetting the scoreboard, 90 00:05:59,450 --> 00:06:02,000 I also get my snake to reset, 91 00:06:02,770 --> 00:06:03,603 Right? 92 00:06:06,160 --> 00:06:07,930 At this point, when I run the code, 93 00:06:07,990 --> 00:06:12,990 you'll notice that it's not behaving quite the way you expect it to. So I can go 94 00:06:13,990 --> 00:06:17,830 ahead and score, and when I die, I get the high score, 95 00:06:18,250 --> 00:06:22,060 but my old snake is still lingering on screen. 96 00:06:22,480 --> 00:06:25,480 So even though we've cleared the segments, 97 00:06:25,690 --> 00:06:30,400 we don't actually get rid of the turtles that are still onscreen. 98 00:06:31,030 --> 00:06:32,710 And in order to get rid of them, 99 00:06:32,740 --> 00:06:37,740 we actually have to send them to a different location. In our snake reset method, 100 00:06:40,000 --> 00:06:42,610 just before we clear our segments, 101 00:06:42,940 --> 00:06:45,340 so while we still have access to all of them, 102 00:06:45,850 --> 00:06:50,850 we're going to use a for loop to loop through all of the segments in the list of 103 00:06:51,100 --> 00:06:56,100 segments and tell each of them to go to a place that is off the screen. 104 00:06:57,940 --> 00:07:01,420 So our screen is only 600 by 600 105 00:07:01,840 --> 00:07:05,590 and I'm going to tell it to go to 1000 X, 1000 Y. 106 00:07:05,950 --> 00:07:10,420 So it's gonna disappear off the screen. So this way, 107 00:07:10,450 --> 00:07:11,283 notice how 108 00:07:11,470 --> 00:07:16,470 when the snake hits one of the walls or when it hits its tail, 109 00:07:16,930 --> 00:07:18,940 instead of sort of just staying there, 110 00:07:18,970 --> 00:07:23,230 it actually disappears into a location that's off the screen. 111 00:07:23,890 --> 00:07:26,890 So that way we can keep track of our high scores, 112 00:07:27,190 --> 00:07:29,680 we can continue to get higher scores, 113 00:07:30,100 --> 00:07:34,000 and if we get a score that's not quite as high as the high score 114 00:07:34,480 --> 00:07:39,220 and we end up dying, then the high score stays as the previous value. 115 00:07:40,180 --> 00:07:44,560 Now, the only thing about this game is that in order to end it, 116 00:07:44,710 --> 00:07:49,570 we have to hit the stop button here. But once we've done that, 117 00:07:49,750 --> 00:07:53,140 it also reveals the crucial flaw in our code. 118 00:07:53,500 --> 00:07:57,580 Because if I run our program again, you can see that, wait, 119 00:07:57,610 --> 00:07:59,410 what happened to the high score, right? 120 00:07:59,620 --> 00:08:03,910 We had a high score of 3 previously. So, huh? 121 00:08:04,300 --> 00:08:08,470 What exactly is happening? Well, the reason is actually quite simple. 122 00:08:09,010 --> 00:08:13,450 We know that if we create a variable, let's say we create a variable called a 123 00:08:13,480 --> 00:08:15,070 set it to equal three, 124 00:08:15,550 --> 00:08:20,320 and then at some point we set a to be from the input. 125 00:08:20,710 --> 00:08:22,540 So now when I run this code, 126 00:08:22,570 --> 00:08:25,780 you can see that initially a is equal to three, 127 00:08:26,200 --> 00:08:31,030 but then the next line I asked the user, 'what do you want a to equals?' 128 00:08:31,030 --> 00:08:34,419 I'm going to make it equal to 12. Now at this point, 129 00:08:34,419 --> 00:08:38,500 if I go ahead and access this variable a inside the console 130 00:08:38,530 --> 00:08:42,880 just by typing a and then hitting enter, you can see it's equal to 12. 131 00:08:43,480 --> 00:08:46,630 Now, similarly, I can add some print statements here. 132 00:08:46,660 --> 00:08:48,370 I can print the value of a 133 00:08:48,700 --> 00:08:53,350 and then also print the value of a after we modify it. So again, 134 00:08:53,530 --> 00:08:57,810 you can see initially it's equal to 3, but then I decided to change it to 12. 135 00:08:58,020 --> 00:08:59,460 So now it's equal to 12. 136 00:09:00,300 --> 00:09:05,300 Now what happens if I rerun the code. A is equal to three 137 00:09:05,880 --> 00:09:06,300 aain. 138 00:09:06,300 --> 00:09:11,300 Its reset itself because the code is being rerun and the previous state is not 139 00:09:13,680 --> 00:09:18,450 being remembered. In our case, we've got this high score variable 140 00:09:18,840 --> 00:09:21,570 which initially starts out as zero. 141 00:09:22,170 --> 00:09:26,580 And at some point during the game as we progress, 142 00:09:26,820 --> 00:09:31,820 we modify this high score variable to equal a new value, 143 00:09:31,920 --> 00:09:32,850 let's say three. 144 00:09:33,480 --> 00:09:37,140 So now if I go ahead and print my high score, 145 00:09:37,620 --> 00:09:39,720 you can see that it's equal to 3. 146 00:09:40,290 --> 00:09:44,130 But as soon as I rerun the code and this goes through, 147 00:09:44,430 --> 00:09:46,980 then all of that progress gets reset. 148 00:09:47,280 --> 00:09:51,900 And now if I print the value of high score, you can see it's again, 149 00:09:51,990 --> 00:09:56,340 equal to zero. So this is what's happening in our program as well. 150 00:09:57,180 --> 00:10:02,180 So how might you keep track of the score if you weren't using Python? 151 00:10:03,150 --> 00:10:03,450 Well, 152 00:10:03,450 --> 00:10:08,400 you might open up a word document and then write down your high score in that 153 00:10:08,400 --> 00:10:11,970 document, close it down, and then the next time you play the game, 154 00:10:12,330 --> 00:10:16,170 open up that file again and see what your previous high score is. 155 00:10:16,710 --> 00:10:18,570 We're going to try and do the same thing, 156 00:10:18,870 --> 00:10:23,870 but using Python to read and write to a file so that we can save our progress 157 00:10:25,800 --> 00:10:29,280 and be able to retrieve our previous high scores 158 00:10:29,370 --> 00:10:34,370 each time we play the snake game. To find out how to do that and to solve this 159 00:10:35,100 --> 00:10:37,470 problem, head over to the next lesson 160 00:10:37,800 --> 00:10:42,270 and we'll talk about how to use Python to open, read, write, 161 00:10:42,360 --> 00:10:44,250 and close files on your system.