附加文件中的每一行

Question

我想在python中追加文件中的每一行例如：

文件.txt

Is it funny?
Is it dog?

预期结果

Is it funny? Yes
Is it dog? No

假设是，否。我是这样做的：

with open('File.txt', 'a') as w:
            w.write("Yes")

但它附加在文件末尾。不是每一行。

编辑 1

with open('File.txt', 'r+') as w:
            for line in w:
                w.write(line + " Yes ")

这是给出结果

Is it funny?
Is it dog?Is it funny?
 Yes Is it dog? Yes 

我不需要这个。它正在添加带有附加字符串的新行。 我需要

Is it funny? Yes
Is it dog? No

Answer 1

你可以写入一个 tempfile 然后替换原来的：

from tempfile import NamedTemporaryFile
from shutil import move
data = ["Yes", "No"]
with open("in.txt") as f, NamedTemporaryFile("w",dir=".", delete=False) as temp:
    # pair up lines and each string
    for arg, line in zip(data, f):
        # remove the newline and concat new data
        temp.write(line.rstrip()+" {}\n".format(arg))

# replace original file
move(temp.name,"in.txt")

您也可以将 fileinput 与 inplace=True 一起使用：

import fileinput
import sys
for arg, line in zip(data, fileinput.input("in.txt",inplace=True)):
    sys.stdout.write(line.rstrip()+" {}\n".format(arg))

输出：

Is it funny? Yes
Is it dog? No

Answer 2

这是一种将现有文件内容复制到临时文件的解决方案。根据需要对其进行修改。然后写回原始文件。 灵感来自here

import tempfile    

filename = "c:\\temp\\File.txt"

#Create temporary file
t = tempfile.NamedTemporaryFile(mode="r+")

#Open input file in read-only mode
i = open(filename, 'r')

#Copy input file to temporary file
for line in i:
  #For "funny" add "Yes"
  if "funny" in line:
      t.write(line.rstrip() + "Yes" +"\n")
  #For "dog" add "No"
  elif "dog" in line:
      t.write(line.rstrip() + "No" +"\n")


i.close() #Close input file

t.seek(0) #Rewind temporary file

o = open(filename, "w")  #Reopen input file writable

#Overwriting original file with temp file contents          
for line in t:
   o.write(line)  

t.close() #Close temporary file