python六剑客：切片、推导列表、map、filter、reduce、lambda

# 列表切片numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]sliced_numbers = numbers[2:7:2]  # 从索引2到7，步长为2print(sliced_numbers)  # 输出：[3, 5, 7]# 字符串切片text = "Hello, World!"sliced_text = text[7:12]  # 从索引7到12print(sliced_text)  # 输出：World

# 创建平方数列表squares = [x**2 for x in range(1, 6)]print(squares)  # 输出：[1, 4, 9, 16, 25]# 筛选偶数列表numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]even_numbers = [x for x in numbers if x % 2 == 0]print(even_numbers)  # 输出：[2, 4, 6, 8, 10]

# 对列表中的每个元素进行平方运算numbers = [1, 2, 3, 4, 5]squared_numbers = list(map(lambda x: x**2, numbers))print(squared_numbers)  # 输出：[1, 4, 9, 16, 25]# 将字符串列表中的单词转换为大写words = ["apple", "banana", "cherry"]uppercase_words = list(map(str.upper, words))print(uppercase_words)  # 输出：['APPLE', 'BANANA', 'CHERRY']

# 筛选列表中的偶数numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]even_numbers = list(filter(lambda x: x % 2 == 0, numbers))print(even_numbers)  # 输出：[2, 4, 6, 8, 10]# 筛选长度大于等于5的字符串words = ["apple", "banana", "cherry", "date", "elderberry"]long_words = list(filter(lambda x: len(x) >= 5, words))print(long_words)  # 输出：['apple', 'banana', 'cherry', 'elderberry']

from functools import reduce# 计算列表中所有元素的累加和numbers = [1, 2, 3, 4, 5]sum_of_numbers = reduce(lambda x, y: x + y, numbers)print(sum_of_numbers)  # 输出：15# 将字符串列表连接成一个长字符串words = ["Hello", ",", " ", "World", "!"]sentence = reduce(lambda x, y: x + y, words)print(sentence)  # 输出：Hello, World!

# 使用lambda表达式创建一个函数，将输入值乘以2double = lambda x: x * 2print(double(5))  # 输出：10# 使用lambda表达式进行两个数的相加add = lambda x, y: x + yprint(add(3, 4))  # 输出：7