Python实现含指定子串的行筛选无输出，求代码修正

文件内容 #

• file1内容：

boy men women
girl women men

• file2内容：

good babyboy
good babygirl
bad babyboy
bad babygirl
xyz
abc

需求说明 #

从file2中筛选同时满足以下条件的行并写入file3：

1. 包含file1每行的第一个单词（boy或girl，可作为其他单词的子串）
2. 包含单词good

预期file3内容：

good babyboy
good babygirl

问题代码（运行后无输出） #

def main():
    input_file_1 = 'file1'
    input_file_2 = 'file2'
    output_file = 'file3'

    with open(input_file_1, 'r') as f:
        lines_1 = f.readlines()
    with open(input_file_2, 'r') as f:
        lines_2 = f.readlines()
    with open(output_file, 'w') as f:
        for line_1 in lines_1:
            words = line_1.split()
            for line_2 in lines_2:
                if words[0] in line_2:
                    if 'good' in line_2:
                        f.write(line_2)

问题原因与修复 #

核心问题 #

代码定义了main()函数但没有调用它，导致程序执行时根本没运行筛选逻辑，自然没有输出。

修复后的代码 #

只需在代码末尾添加main()调用即可：

def main():
    input_file_1 = 'file1'
    input_file_2 = 'file2'
    output_file = 'file3'

    with open(input_file_1, 'r') as f:
        lines_1 = f.readlines()
    with open(input_file_2, 'r') as f:
        lines_2 = f.readlines()
    with open(output_file, 'w') as f:
        for line_1 in lines_1:
            words = line_1.split()
            for line_2 in lines_2:
                if words[0] in line_2 and 'good' in line_2:
                    f.write(line_2)

# 调用main函数
main()

优化建议（可选） #

原代码嵌套循环效率较低，可先收集file1的关键词到集合，再遍历file2一次完成筛选，逻辑更清晰且高效：

def main():
    input_file_1 = 'file1'
    input_file_2 = 'file2'
    output_file = 'file3'

    # 收集file1每行的第一个单词
    keywords = set()
    with open(input_file_1, 'r') as f:
        for line in f:
            first_word = line.strip().split()[0]
            keywords.add(first_word)

    # 筛选file2的行并写入file3
    with open(input_file_2, 'r') as f_in, open(output_file, 'w') as f_out:
        for line in f_in:
            has_keyword = any(key in line for key in keywords)
            if has_keyword and 'good' in line:
                f_out.write(line)

main()

内容的提问来源于stack exchange，提问作者Vivek