Python for Absolute Beginners Transcripts
Chapter: Organizing and reusing code with functions
Lecture: Checking for a win

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0:00 Well, that was fun.
0:01 And now this next part we're going to right here
0:02 what we have to do is we have to test for a winner, right?
0:05 We've already gotten the rows
0:06 we've verify that they're valid
0:08 that they are among the three options
0:10 that we can do with our game.
0:12 But how do we test who's won?
0:14 Well, it turns out, the most straightforward way to do this
0:17 is actually really complicated and not very pretty.
0:21 But what we're going to do is we're going to build this
0:22 and then we're going to improve on it
0:24 and improve upon it, okay.
0:25 So let me paste out some little basic steps that say
0:29 here's how this game is played.
0:30 So if somebody plays a rock
0:32 and then the other person plays a rock, it's at tie
0:35 the other person plays a paper, they lose.
0:37 Other person plays a scissors, they win.
0:40 But let's go over here.
0:41 And first we're going to need a way to indicate
0:43 who won this round.
0:45 So we'll say winner equals, now in Python if we want to say
0:49 we don't know what this value is
0:51 it doesn't point to anything.
0:52 Is it player_1? Is it player_2?
0:54 We don't know, it's not set yet.
0:56 The way you do that, as you say, it's none.
0:58 This means remember in the Python tutor
1:01 where we had all those arrows pointing at things
1:02 basically the conceptual idea here is this point nowhere
1:06 technically there's a thing that's created
1:08 that's called none, but that's the idea.
1:09 So that it says, usually know here this goes right now.
1:12 So what we want to do, is we want to convert this bit
1:15 into some if statements.
1:17 So let's do this first one now.
1:18 Notice there's a tie, there's a tie, and there's a tie.
1:22 So scissors scissors tie, paper paper tie, rock rock tie
1:26 Though, let's go over here.
1:28 And we'll say if, oh, what is it?
1:29 Row one is the same as or equal to.
1:32 So double equals, remember, row two
1:35 then we'll print a game was a tie
1:38 or the play was tied.
1:40 All right, so now we want to have another case.
1:43 On the other hand, what are we going to do?
1:45 Well, we're going to start out by just doing basically
1:47 this test in software.
1:49 I'm going to show you something much better later.
1:51 But remember that requires more ideas
1:53 that we're going to get to.
1:54 So if I can say row one, if this happens to be rock
1:58 now be careful, that and that is not the same.
2:02 Though if we say capital R rock
2:04 that's a totally different variable value
2:06 than lowercase rock.
2:07 So we can actually even verify that a little bit better.
2:10 So we could take away some of those challenges
2:13 that the players might have.
2:14 So if they type capital rock or something
2:16 we could also go over here and say I want to change row one
2:19 let's make it whatever it is, but we want to lowercase it.
2:22 So that's a string thing.
2:24 We also might want to say, well
2:25 if they put a space accidentally and then hit Enter
2:28 that's okay too, We're just going to ignore that.
2:30 So you can say that by saying strip.
2:31 That we go to this value, and so by it we say
2:34 row one is its current value, but lowercase
2:36 and then take away all the spaces, tabs, and so on.
2:39 That'll make things a little easier.
2:40 So we don't have to worry about checking whether or not
2:43 that's a capital or lowercase R
2:45 whatever they type is always lowercase rock
2:47 because what we just did there, right.
2:49 Now if that's the case
2:51 we have more tests that we have to do
2:52 so we have to say if row two is, ah, which one, paper.
2:57 If row two is paper, player_1 is a loser
3:01 which makes player to the winner.
3:02 So we'll say winner equals player_2.
3:05 Wow, right.
3:06 Else, now we could just say else because technically
3:09 they're not going to be the same.
3:11 But let's say make it really clear.
3:14 If this is going to be scissors, if it scissors
3:18 the person whose perspective we're looking at this from
3:21 is going to be the winner.
3:22 The winner is player_1, okay?
3:25 We need to just do that over again for paper
3:28 I'm going to move this up for now.
3:29 So you all have this as a little reference.
3:33 Like so, and going to be exactly the same.
3:36 This is going to be the next one is paper.
3:39 This is rock.
3:41 It's paper and this is rock
3:42 then the winner is the person playing that row.
3:45 And still like this.
3:48 There we go.
3:49 So if I play paper, other person plays scissors, I lose.
3:52 If I play rock or if they play rock, the paper covers it
3:56 I win, right. Do one more and then we'll have it all, okay.
3:58 I told you, this is not pretty
4:00 we're going to make it awesome.
4:01 Hang in there.
4:02 But right now it's not pretty.
4:03 The last one is if I were to play scissors
4:07 and they play rock, they're going to smash the scissors
4:10 so they win. If they play paper, I'm cutting the paper
4:13 so I win, all right.
4:15 And let's just do a little print out here.
4:17 So this will be the end of the round, a game is over.
4:20 Say if, one more test here, if not winner
4:23 or something like this, winner is none
4:27 then what we can do is we'll print it was a tie, else
4:31 and whatever the winner is, takes the game, right?
4:35 Though, we've determined the name of the player.
4:37 So that won, we're just going to say they won.
4:40 This is what happens if there's a tie.
4:41 Otherwise, somebody has won, let's just say who it is.
4:44 Wow, okay, that does not look pretty, does it?
4:47 Well, we're going to play more of that
4:49 and make it much, much nicer.
4:50 But let's go ahead and play a game
4:51 and see how we're doing here.
4:52 Remember, we're going to build it up
4:54 kind of the yucky straightforward way
4:56 and then we're going to make it way nicer with all the ideas
4:58 like functions or what not that we're studying.
5:00 My name is Michael, other players Sam.
5:03 I'm going to play paper.
5:05 Let's pick some situation where Sam is going to win
5:07 and to win this round he has to play scissors.
5:10 Michael row is paper, Sam row is scissors.
5:12 The game is over and Sam takes the game, awesome.
5:15 Let's play one more round.
5:17 It's getting tiresome to already typed in my name
5:19 and the other players name, that's fine.
5:21 Let's play paper and he's going to play rock
5:24 which case I should win.
5:25 Michael row is paper, Sam row is rock.
5:27 The game is over, Michael takes the win
5:29 with a decisive throw of rock, no, of paper.
5:33 Fun, fun fun game.
5:34 Okay, so it looks like it's working.
5:36 There's a few shortcomings here.
5:38 One this is you know, Sam can always just see
5:41 what I type in and go well you know what
5:43 it's time to play some scissors or something like that.
5:47 The other one is, what if I want to play by myself?
5:49 I don't have any friends right now
5:51 that want to play Rock, Paper Scissors
5:53 though I want to play by myself
5:54 so we can make the computer do scissors.
5:56 A few basic enhancements there.
5:57 The other one, it's very common that Rock, Paper, Scissors
6:00 is done in a best of style, right?
6:04 So, first person to win three rounds
6:06 first person to win five rounds and so on.
6:08 Well, what we've written so far, is not easy to do
6:12 but we'd have to like replicate this over and over
6:15 or do some kind of loop or something.
6:17 So we're going to do a little bit of work here as well.
6:20 More to do but still, Rock, Paper Scissors is coming along.