循环

enumerate

该函数用于在迭代过程中获取每个元素的索引和值，返回一个可迭代对象，该对象生成一个包含索引和值的元组。

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enumerate(iterable,start=0)

其中，iterable 是要遍历的可迭代对象，例如列表、元组、字符串等。而 start 是可选参数，用于指定开始的索引，默认值是 0。

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fruits = ['apple', 'banana', 'orange']

for index, fruit in enumerate(fruits):
    print(f'Index: {index}, Fruit: {fruit}')

# Index: 0, Fruit: apple
# Index: 1, Fruit: banana
# Index: 2, Fruit: orange

在这个例子中，enumerate(fruits) 返回了一个可迭代对象，其中每个元素都是一个包含索引和对应值的元组。通过使用 index 和 fruit 分别接收索引和值，可以在循环中打印每个水果的索引和值。

除了使用默认的开始索引 0，你还可以使用 start 参数来指定开始的索引值。下面的示例将开始索引设置为 1：

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fruits = ['apple', 'banana', 'orange']

for index, fruit in enumerate(fruits, start=1):
    print(f'Index: {index}, Fruit: {fruit}')

# Index: 1, Fruit: apple
# Index: 2, Fruit: banana
# Index: 3, Fruit: orange

例题：获取10-20之间的prime number，如果不是质数，指出他们的因子。

for-else

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for number in range(10, 20):
    for factor1 in range(2, number):
        if number % factor1 == 0:
            factor2 = number / factor1
            print(f'{factor1}*{factor2:0.0f}={number}')
            break
    else:
        print(f'{number} is a prime number')

for-if-else

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for number in range(10, 20):
    for factor1 in range(2, number):
        if number % factor1 != 0:
            print(f'{number} is a prime number')
            break
        else:
            factor2 = number / factor1
            print(f'{factor1}*{factor2:0.0f}={number}')
            break

while-else

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number = 10
while number < 20:
    factor1=2
    while factor1<20:
        if number%factor1==0:
            factor2=number/factor1
            print(f'{factor1}*{factor2:0.0f}={number}')
            break
        factor1+=1
    else:
        print(f'{number} is a prime number')
    number+=1

刷题

第1天的作业打卡

来自quiz_1-2.pdf

待读取的文件内容可以这样写：

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John Dick,M
Jane Smith,F
Michael Johnson,M

注意

.strip()和.removesuffix()都是Python字符串操作，分别用于删除字符串两端的空白字符和指定的后缀，其中，.removesuffix() 是在Python 3.9中引入的。

.strip() 方法用于删除字符串开头和结尾的空白字符，包括空格、制表符、换行符等。

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text = "  Hello, World!  "
print(text.strip())  # 输出: "Hello, World!"

.removesuffix('\n') 方法用于删除字符串末尾的指定后缀。

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text = "Hello, World!\n"
print(text.removesuffix('\n'))  # 输出: "Hello, World!"
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import sys
from os.path import exists

def print_rhombus(space_number, symbol):
    print('Here is a rhombus:')
    print()
    # 方法一：枚举
    # half_layers=2
    # print(' ' * (space_number + 2) + '*')
    # print(' ' * (space_number + 1) + '*' + ' ' * 1 + '*')
    # print(' ' * (space_number + 0) + '*' + ' ' + symbol + ' ' + '*')
    # print(' ' * (space_number + 1) + '*' + ' ' * 1 + '*')
    # print(' ' * (space_number + 2) + '*')

    # 方法二：循环
    half_layers=2
    print(' ' * (space_number + half_layers) + '*')
    for i in range(half_layers-1,0,-1):
        print(' '*(space_number+i)+'*'+' '*(2*(half_layers-i)-1)+'*')

    # (2*half_layers-2)/2=half_layers-1
    print(' ' * (space_number + i-1) + '*' + ' '*(half_layers-1) + symbol + ' '*(half_layers-1) + '*')

    for i in range(1,half_layers):
        print(' '*(space_number+i)+'*'+' '*(2*(half_layers-i)-1)+'*')

    print(' ' * (space_number + half_layers) + '*')
    print()

def print_lines(file_name):
    print('Here are the people listed in the file:')
    with open(file_name) as file:
        for line in file:
            line = line.strip()
            # 判断不是空行并且包含逗号
            if line and ',' in line:
                name, gender = line.split(',')
                last_name, first_name = name.split()
                gender = 'Mr.' if gender.strip() == 'M' else "Mrs"
                print(f"{gender} {first_name} {last_name}")

if __name__ == '__main__':
    try:
        space_number = int(input("Enter a positive integer (possibly 0): "))
        symbol = input("Input a symbol: ").removesuffix("\n")
        if space_number < 0 or symbol is None:
            raise ValueError
    except ValueError:
        print("Input is not an positive integer, giving up.")
        sys.exit()
    file_name = input('Input the name of a file in the working directory: ').removesuffix('\n')
    if not exists(file_name):
        print('Incorrect directory, giving up.')
        sys.exit()

    print_rhombus(space_number, symbol)
    print_lines(file_name)

Classifying elements in a list

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from random import randint, seed

if __name__ == '__main__':
    seed_value = int(input("Input a seed for the random number generator: "))
    element_number = int(input("How many elements do you want to generate? "))

    res = []
    seed(seed_value)
    lst = [randint(0, 20) for _ in range(0, element_number)]
    print(lst)

    first_interval, second_interval, third_interval, forth_interval = 0, 0, 0, 0

    for item in lst:
        if item <= 4 and item >= 0:
            first_interval += 1
        elif item <= 9 and item >= 5:
            second_interval += 1
        elif item <= 14 and item >= 10:
            third_interval += 1
        else:
            forth_interval += 1

    print(
        f"There is {first_interval} element between 0 and 4." if first_interval > 0 else "There is no element between 0 and 4.")
    print(
        f"There is {second_interval} element between 5 and 9." if second_interval > 0 else "There is no element between 5 and 9.")
    print(
        f"There is {third_interval} element between 10 and 14." if third_interval > 0 else "There is no element between 10 and 14.")
    print(
        f"There is {forth_interval} element between 15 and 19." if forth_interval > 0 else "There is no element between 15 and 19.")

快来参与讨论吧~