在Python中从.txt文件中删除页码

Question

I am trying to load a .txt file of an ebook and remove lines that contain page numbers. The book looks like:

2
Words
More words.

More words.

3
More words.

Here is what I have so far:

x = 1

with open("first.txt","r") as input:
    with open("last.txt","wb") as output: 
        for line in input:
            if line != str(x) + "\n":
                output.write(line + "\n")
                x + x + 1

My output file comes out with all of the white space (new lines) removed (which I don't want) and it does not even remove the numbers. Does anyone have any ideas? Thanks!

Answer 1

1) You don't have to open your file for binary open("last.txt","wb") -> open("last.txt","w") 2) x + x + 1 -> x += 1

But, you could do it far simpler

with open("first.txt","r") as input:
    with open("last.txt","w") as output: 
        for line in input:
            line = line.strip() # clear white space
            try: 
                int(line) #is this a number ?
            except ValueError:
                output.write(line + "\n")

Answer 2

Check if you can convert the line to an integer and skip this line if that succeeds. Not the quickest solution, but should work.

try:
   int(line)
   # skip storing that line
   continue
except ValueError:
   # save the line to output

Answer 3

Use regular expressions to ignore lines that contain just a number.

import sys
import re

pattern = re.compile("""^\d+$""")

for line in sys.stdin:
    if not pattern.match(line):
        sys.stdout.write(line)

Answer 4

Improved solution - one less indentation level, avoid unnecessary strip and string summation, explicit exception caught.

with open("first.txt","r") as input_file, open("last.txt","w") as output_file:
    for line in input_file:
        try: 
            int(line)
        except ValueError:
            output_file.write(line)