This article is for Django Girls Japan Python beginners, This is a study session material for "Let's make a rock-paper-scissors game with Python". In addition, since the author is also a beginner, we apologize for any problems. Namer environment: Windows 10 python3.5 In addition, this article is a page of answers and explanations to the problems in the article of Janken Poi in Python.

Answer code

The problem page is here

# !/usr/bin/env python
# -*- coding: utf-8 -*-

import random

dic = {"a": "Goo", "b": "Choki", "c": "Par"}

print("Janken")
print("a=Goo b=Choki c=Enter par a, b, or c")
user = input('>>>  ')
user = user.lower()

try:
    user_choice = dic[user]

    choice_list = ["a", "b", "c"]
    pc = dic[random.choice(choice_list)]

    draw = 'DRAW'
    win = 'You Win!!'
    lose = 'You lose!!'

    if user_choice == pc:
        judge = draw
    else:
        if user_choice == "Goo":
            if pc == "Choki":
                judge = win
            else:
                judge = lose

        elif user_choice == "Choki":
            if pc == "Par":
                judge = win
            else:
                judge = lose

        else:
            if pc == "Goo":
                judge = win
            else:
                judge = lose

    print("You chose%s" % user_choice)
    print("The computer chose%s" % pc)
    print("Result is%s" % judge)
except:
    print("Please enter a, b or c.")

The code above is just an example. I think there are various ways to describe it, so I hope you will recognize it as one of the methods.

Commentary

Creating a dictionary

dic = """Question 1: Please make a dictionary where 1 is Goo 2 and Choki 3 is Par."""

↓ Ask the user to enter a, b, or c. Since the key of the dictionary is a, b, or c, the keys are a, b, and c, and the value is set. Create a dictionary with goo, choki, and par.

input()

The print statement is a statement that prints the contents described in ().

user = input('>>> ') Program execution is interrupted at the line where input () is written, and waits for keyboard input. This time, there is a two-line print statement before input (), so it will be interrupted with the print statement and the >>> specified in () of input () displayed.

The input () function stores the contents input from the keyboard in the variable (user this time).

In addition, this time, kindly to the user ... so that you can enter uppercase letters, user = Converting characters entered with user.lower () to lowercase.

Exception handling

If the content entered by the user is not a, b, or c, there is no key in the dictionary. An error will occur and the program will be interrupted.

This spoils the fun (?) Game.

There are various ways to avoid this, but this time we will use exception handling.

Getting dictionary value using variables

user_choice = """Question 2: Is it goo using dic from the number entered by the user?
Get the choki or par letters"""

The method of acquiring the value of the dictionary is the dictionary name [key]. This time I will use Therefore, the dictionary name is dic. The key is user because it is the information received by input ().

Therefore, in order to obtain the value of Goo, Choki, or Par from the information selected by the user,

user_choice = dic[user]

It is described as.

Distinguish goo, choki, and par from the hands of a computer

pc = """Question 3: Using the imported random, let the PC choose a number,
And get the string of goo, choki or par"""

↓

There are other ways to choose a computer hand, using the random module, This time, since the list is prepared in python first, use random.choice ().

One element is randomly extracted from the choice_list with random.choice (choice_list). The extracted element is used for the key of the dictionary created earlier.

Therefore ... From the hand selected by the computer by setting dic [random.choice (choice_list)] You can get value.

Conditional branch with if statement

"""Question 4: Compare the user's hand with the PC's hand to get the result.
The result is to create a variable called judge and do one of the above draw win lose
Please put it in a variable."""

↓ Arrows of the same color are the conditions. (I'm sorry. It's a little difficult to understand .. I'll update it if I can make it easier to understand ...) python I will make this judgment first, and then I will win or lose, so I will make a detailed judgment below else:.

String concatenation

Concatenation using% s% d

This time, I'm using a slightly older type of string concatenation method. Even now, it is described as an example on various sites. I still use it a lot (because it's easy ... ^^;), so I'll explain it.

"What you chose%s" % user_choice

There is a description of% s in the character string enclosed in "" (''is OK). Specify the character you want to embed in this% s part (this time, the character string in the user_choice variable). To specify, simply enclose it in "", enter%, and then enter the character you want to embed.

So what if you want to embed multiple characters?

a = "women"
b = 40

"A %s does not become interesting until she is over %d" % (a, b)

→A women does not become interesting until she is over 40 *% d embeds int value

It is OK if you pass% s and% d in the specified order, after the% after the character string (listed in the order of embedding, separated by commas).

** By the way, the English translation of ↑ is "Women become interesting only after 40." (It doesn't matter, but lol)

Other connection methods

Concatenation using operators

You can also use operators for strings. Actually ...

"You chose" + user_choice

Even if you just say, there is no problem with this content.

You can also use * (multiplication) for the character string. For example, if the variable of user_choice is "Goo"

user_choice * 3

Then

"Goo Goo Goo"

It will be.

Concatenation using format

Well ... In some cases, you may want to embed the same string in several places.

"My name is {0}.  Hallo {0}!! My Name is {1}".format("Taro", "Hanako")

→ "My name is Taro. Hallo Taro!! My Name is Hanako"

The number in {} indicates the room number of the tuple after formatting. If you use% s, the inside of () is the same as ("Taro", "Taro", "Hanako"). It is necessary to list more than one, but if you use format, as above, This is convenient because you don't have to write "Taro" twice.

If there are many places you want to embed and it is difficult to manage by room number, etc. It is also possible to specify by keyword.

"My name is {name1}.  Hallo {name1}!! My Name is {name2}".format(name1= "Taro", name2 =  "Hanako")