python - 在字符串匹配后将行插入文件

Question

我正在尝试在文件的行内搜索子字符串，并在找到的行之后立即插入相似的行。尽管有使用 fileinput 方法的类似解决方案，但我不知道如何在我的案例中使用它。

这是我尝试过的:

list = ["abc", "pqr", "xyz"]

inputfile = open (somefile.txt, 'a+')
for line in <inputfile>:    
    if 'stringstosearch' in line:
       for <item> in list:
               new_line = "new_line with %s" %(item)        
               inputfile.write(new_line + "\n") 
    break
inputfile.close()

例如，如果文本文件是:

Torquent scelerisque aptent hac rhoncus vel
Turpis vestibulum tellus laoreet mollis conubia facilisis tempor nec semper
In mi mauris etiam quisque sem congue est velit lacus convallis amet ante ad
Integer maecenas semper quisque nisi hendrerit, libero feugiat cursus euismod accumsan
Dui sed magna vivamus augue ac quisque ac mauris torquent eros taciti
Conubia curae vel himenaeos dictumst sed at

string to search = "mauris etiam quisque"
list = ["abc", "pqr", "xyz" ]

文件写入后的预期输出:

Torquent scelerisque aptent hac rhoncus vel
Turpis vestibulum tellus laoreet mollis conubia facilisis tempor nec semper
In mi mauris etiam quisque sem congue est velit lacus convallis amet ante ad
new_line with abc
new_line with pqr
new_line with xyz
Integer maecenas semper quisque nisi hendrerit, libero feugiat cursus euismod accumsan
Dui sed magna vivamus augue ac quisque ac mauris torquent eros taciti
Conubia curae vel himenaeos dictumst sed at

Answer 1

你不能只插入文件中间，所以对于小文件，首先要完整地读取文件。然后以写入模式打开同一个文件，并在找到字符串时追加。

list = ["abc", "pqr", "xyz"]

inputfile = open('somefile.txt', 'r').readlines()
write_file = open('somefile.txt','w')
for line in inputfile:
    write_file.write(line)
    if 'stringstosearch' in line:
       for item in list:
            new_line = "new_line with %s" %(item)        
            write_file.write(new_line + "\n") 
write_file.close()