Python脚本删除段落和文件末尾之间的多个空行

Question

I wrote a python script to capture the data I want but I have a resulting text file that contains multiple paragraphs but each paragraph is separated by varying blank lines - anywhere from 2 to 8.

My file also has multiple blank lines at the end of the file.

I would like Python to leave no more than 2 blank lines between paragraphs and and no blank lines at the end of the text file.

I have experimented with a loop and line.strip, replace etc but I clearly have little idea how to put this together.

examples of what I have been using so far

wf = open(FILE,"w+")
for line in wf:
         newline = line.strip('^\r\n')
         wf.write(newline)
         wf.write('\n')

Answer 1

Here's some untested code:

import re

new_lines = re.compile('\n{2,9}')

with open(FILE) as f:
    contents = f.read()
contents = re.sub(new_lines, '\n\n\n', contents.strip())
with open(FILE, 'w') as f:
    f.write(contents)

First the blank lines at the end are removed. Then the regular expression matches instances of 2 to 9 newlines in the contents of the file, and replaces these with 3 newlines by the re.sub() function.

Answer 2

It's actually easier to remove all blank lines and then insert two blank lines between paragraphs (and none at the end) than counting all blank lines and only removing if there's more than two. Unless you're dealing with huge files I don't think there's going to be any performance difference between the two approaches. Here's a quick and dirty solution using re :

import re
# Reads from file
f = open('test.txt', 'r+')
txt = f.read()
# Removes all blank lines
txt = re.sub(r'\n\s*\n', '\n', txt)
# Adds two blanks between all paragraphs
txt = re.sub(r'\n', '\n\n\n', txt)
# Removes the blank lines from the EOF
txt = re.sub(r'\n*\Z', '', txt)
# Writes to file and closes
f.write(txt)
f.close()

Before:

One line below

None below
Three below



EOF with one blank line below (stackoverflow's code thingy omits it)

After:

One line below


None below


Three below


EOF with one blank line below

Answer 3

I know the answer requested is python, but I believe that might be an overkill.

Why not preprocess the file directly on your shell ? Use grep or sed or awk to accomplish this.

Here is the grep version:

$ grep -v '^$' input.txt > output.txt

Here is a quick reference I found

Answer 4

So far, the question has not really been answered. Here is a solution that works, but I think it could be better.

newtext = ''    
counter = 0
for line in text.splitlines():
    line = line.strip()
    if len(line)==0:
        counter += 1
        if counter<=2:
            newtext += line + '\n'
    else:
        newtext += line + '\n'
        counter = 0