[英]Deleting n number of lines after specific line of file in python
I am trying to remove a specific number of lines from a file. 我正在尝试从文件中删除特定数量的行。 These lines always occur after a specific comment line. 这些行总是出现在特定的注释行之后。 Anyways, talk is cheap, here is an example of what I have. 无论如何,谈话很便宜,这是我所拥有的例子。
FILE: -- 文件:-
randomstuff
randomstuff2
randomstuff3
# my comment
extrastuff
randomstuff2
extrastuff2
#some other comment
randomstuff4
So, I am trying to remove the section after # my comment
. 因此,我试图在#my # my comment
之后删除该部分。 Perhaps there is someway to delete a line in r+
mode? 也许有某种方式可以在r+
模式下删除一行?
Here is what I have so far 这是我到目前为止的
with open(file_name, 'a+') as f:
for line in f:
if line == my_comment_text:
f.seek(len(my_comment_text)*-1, 1) # move cursor back to beginning of line
counter = 4
if counter > 0:
del(line) # is there a way to do this?
Not exactly sure how to do this. 不确定如何执行此操作。 How do I remove a specific line? 如何删除特定行? I have looked at this possible dup and can't quite figure out how to do it that way either. 我已经看过这种可能的重复 ,也无法完全弄清楚该怎么做。 The answer recommends you read the file, then you re-write it. 答案建议您阅读文件,然后重新编写。 The problem with this is they are checking for a specific line when they write. 问题是他们在写时正在检查特定行。 I cant do that exactly, plus I dont like the idea of storing the entire files contents in memory. 我不能完全做到这一点,而且我不喜欢将整个文件内容存储在内存中的想法。 That would eat up a lot of memory with a large file (since every line has to be stored, rather than one at a time). 这将占用一个大文件的大量内存(因为必须存储每一行,而不是一次存储一行)。
Any ideas? 有任何想法吗?
You can make a small modification to your code and stream the content from one file to the other very easily. 您可以对代码进行少量修改,然后非常轻松地将内容从一个文件传输到另一个文件。
with open(file_name, 'r') as f:
with open(second_file_name,'w') a t:
counter = 0
for line in f:
if line == my_comment_text:
counter = 3
elif: counter > 0
counter -= 1
else:
w.write(line)
You can use the fileinput
module for this and open the file in inplace=True
mode to allow in-place modification: 您可以为此使用fileinput
模块,并以fileinput
inplace=True
模式打开文件以允许就地修改:
import fileinput
counter = 0
for line in fileinput.input('inp.txt', inplace=True):
if not counter:
if line.startswith('# my comment'):
counter = 4
else:
print line,
else:
counter -= 1
Edit per your comment "Or until a blank line is found": 按照您的编辑 评论 “或者直到一个空行发现”:
import fileinput
ignore = False
for line in fileinput.input('inp.txt', inplace=True):
if not ignore:
if line.startswith('# my comment'):
ignore = True
else:
print line,
if ignore and line.isspace():
ignore = False
I like the answer form @Ashwini. 我喜欢答案形式@Ashwini。 I was working on the solution also and something like this should work if you are OK to write a new file with filtered lines: 我也在研究解决方案,如果您可以编写包含过滤行的新文件,则类似的内容应该可以工作:
def rewriteByRemovingSomeLines(inputFile, outputFile):
unDesiredLines = []
count = 0
skipping = False
fhIn = open(inputFile, 'r')
line = fhIn.readline()
while(line):
if line.startswith('#I'):
unDesiredLines.append(count)
skipping = True
while (skipping):
line = fhIn.readline()
count = count + 1
if (line == '\n' or line.startswith('#')):
skipping=False
else:
unDesiredLines.append(count)
count = count + 1
line = fhIn.readline()
fhIn.close()
fhIn = open(inputFile, 'r')
count = 0
#Write the desired lines to a new file
fhOut = open(outputFile, 'w')
for line in fhIn:
if not (count in unDesiredLines):
fhOut.write(line)
count = count + 1
fhIn.close()
fhOut.close
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