7、Python编程：嵌套列表推导式、函数与文件操作全解析

Python编程：嵌套列表推导式、函数与文件操作全解析

1. 嵌套列表推导式

嵌套列表推导式能将整个操作封装在一个单一的嵌套结构中。例如：

all_data = [['Maria', 'John'], ['Natalia', 'Tom']]
result = [name for names in all_data for name in names if name.count("a") >= 2]
print(result)  # 输出: ['Maria', 'Natalia']

嵌套列表推导式的 for 部分按嵌套顺序排列，过滤条件放在最后。再看将整数元组列表“扁平化”为简单整数列表的例子：

some_tuples = [(1, 2, 3), (4, 5, 6), (7, 8, 9)]
flattened = [x for tup in some_tuples for x in tup]
print(flattened)  # 输出: [1, 2, 3, 4, 5, 6, 7, 8, 9]

这与使用嵌套 for 循环的效果相同：

flattened = []
for tup in some_tuples:
    for x in tup:
        flattened.append(x)

不