读/写文本文件

Question

我试图更改文本文件中的一些行而不影响其他行.这就是文本文件中名为"text.txt"的内容

this is  a test1|number1
this is a test2|number2
this is a test3|number2
this is a test4|number3
this is a test5|number3
this is a test6|number4
this is a test7|number5
this is a test8|number5
this is a test9|number5
this is a test10|number5

我的目标是更改第4行和第5行,但保持其余部分相同.

mylist1=[]
for lines in open('test','r'):
    a=lines.split('|')
    b=a[1].strip()
    if b== 'number3':
        mylist1.append('{}|{} \n'.format('this is replacement','number7'))
    else:
         mylist1.append('{}|{} \n'.format(a[0],a[1].strip()))
myfile=open('test','w')
myfile.writelines(mylist1)

即使代码有效,我想知道是否有更好更有效的方法来做到这一点？是否可以通过行号读取文件？

Answer 1

你可以改进的并不多.但是您必须将所有行写入新文件,无论是更改还是未更改.小改进将是:

• 使用with声明;
• 避免在列表中存储行;
• lines在else条款中写入没有格式化(如果适用).

应用以上所有内容:

import shutil
with open('test') as old, open('newtest', 'w') as new:
    for line in old:
        if line.rsplit('|', 1)[-1].strip() == 'number3':
            new.write('this is replacement|number7\n')
        else:
            new.write(line)
shutil.move('newtest', 'test')