Question

我无法让python读取特定的行。我正在做的是这样的事情：

lines of data not needed
lines of data not needed
lines of data not needed

--------------------------------------
    ***** REPORT 1 *****
--------------------------------------

[key] lines of interest are here
[key] lines of interest are here
[key] lines of interest are here
[key] lines of interest are here
[key] lines of interest are here      #This can also be the EOF

--------------------------------------    
    ***** REPORT 2 *****
--------------------------------------

lines of data not needed
lines of data not needed
lines of data not needed         #Or this will be the EOF

我尝试的是：

flist = open("filename.txt").readlines()

for line in flist:
  if line.startswith("\t**** Report 1"):
    break
for line in flist:
  if line.startswith("\t**** Report 2"):
    break
  if line.startswith("[key]"):
    #do stuff with data

但是，当文件以没有结束分隔符结束时出现问题...例如，当没有显示报告＃2时。什么是更好的方法？

Answer 1

一个看起来应该覆盖你的问题的轻微修改：

flist = open("filename.txt").readlines()

parsing = False
for line in flist:
    if line.startswith("\t**** Report 1"):
        parsing = True
    elif line.startswith("\t**** Report 2"):
        parsing = False
    if parsing:
        #Do stuff with data

如果你想避免解析“ * 报告1”......本身，只需将开始条件放在if parsing之后，即

flist = open("filename.txt").readlines()

parsing = False
for line in flist:

    if line.startswith("\t**** Report 2"):
        parsing = False
    if parsing:
        #Do stuff with data 
    if line.startswith("\t**** Report 1"):
        parsing = True

Answer 2

在这里可以使用itertools模块替代。
尽管这里的问题需要检查[key]，但我还要添加itertool.islice（），以表明当用户有一些先入之先时，可以在开始阅读标记之后跳过几行信息。

from itertools import takewhile, islice, dropwhile

with open('filename.txt') as fid:
    for l in takewhile(lambda x: '***** REPORT 2 *****' not in x, islice(dropwhile(lambda x: '***** REPORT 1 *****' not in x, fid), 1, None)):
        if not '[key]' in l:
            continue
        print(l)

Python读取两个字符串之间的特定文本行

2 个答案: