17

我不是在谈论特定的行号,因为我正在读取具有相同格式但长度不同的多个文件。
假设我有这个文本文件:

Something here...  
... ... ...   
Start                      #I want this block of text 
a b c d e f g  
h i j k l m n  
End                        #until this line of the file
something here...  
... ... ...  

我希望你知道我的意思。我正在考虑遍历文件,然后使用正则表达式搜索以找到“开始”和“结束”的行号,然后使用 linecache 从开始行读取到结束行。但是如何获得行号?我可以使用什么功能?

4

4 回答 4

37

如果您只是想要 and 之间的文本块StartEnd您可以执行以下简单操作:

with open('test.txt') as input_data:
    # Skips text before the beginning of the interesting block:
    for line in input_data:
        if line.strip() == 'Start':  # Or whatever test is needed
            break
    # Reads text until the end of the block:
    for line in input_data:  # This keeps reading the file
        if line.strip() == 'End':
            break
        print line  # Line is extracted (or block_of_lines.append(line), etc.)

事实上,您无需操作行号即可读取开始和结束标记之间的数据。

逻辑(“读到……”)在两个块中重复,但它非常清晰和有效(其他方法通常涉及检查某些状态[在块之前/块内/到达块结束],这会导致时间损失)。

于 2011-09-26T18:29:28.600 回答
5

这是可行的方法:

data_file = open("test.txt")
block = ""
found = False

for line in data_file:
    if found:
        block += line
        if line.strip() == "End": break
    else:
        if line.strip() == "Start":
            found = True
            block = "Start"

data_file.close()
于 2011-09-26T18:23:48.697 回答
3

你可以很容易地使用正则表达式。您可以根据需要使其更健壮,下面是一个简单的示例。

>>> import re
>>> START = "some"
>>> END = "Hello"
>>> test = "this is some\nsample text\nthat has the\nwords Hello World\n"
>>> m = re.compile(r'%s.*?%s' % (START,END), re.S)
>>> m.search(test).group(0)
'some\nsample text\nthat has the\nwords Hello'
于 2011-09-26T20:23:02.843 回答
1

这应该是你的开始:

started = False
collected_lines = []
with open(path, "r") as fp:
     for i, line in enumerate(fp.readlines()):
         if line.rstrip() == "Start": 
             started = True
             print "started at line", i # counts from zero !
             continue
          if started and line.rstrip()=="End":
             print "end at line", i
             break
          # process line 
          collected_lines.append(line.rstrip())

生成器采用enumerate生成器并枚举迭代。例如。

  print list(enumerate("a b c".split()))

印刷

   [ (0, "a"), (1,"b"), (2, "c") ]

更新

海报要求使用正则表达式来匹配“===”和“======”之类的行:

import re
print re.match("^=+$", "===")     is not None
print re.match("^=+$", "======")  is not None
print re.match("^=+$", "=")       is not None
print re.match("^=+$", "=abc")    is not None
print re.match("^=+$", "abc=")    is not None
于 2011-09-26T18:22:51.373 回答