使用Python从文本文件中删除一行

问题描述

我有一个文件，每行以数字开头。用户可以通过输入用户想要删除的行号删除一行。

我遇到的问题是设置打开它的模式。当我使用 a + 时，原始内容仍然存在。但是，在文件末尾加上了我想保留的行。另一方面，当我使用 w + 时，整个文件被删除。我敢肯定有一个比 w + 模式更好的方法，删除所有内容，然后重新打开它并添加行。

  def DeleteToDo（self）：
 print您要删除哪个项目？ 
 DeleteItem = raw_input（>）＃选择要删除的行号
打印您确定要删除数字+ DeleteItem +（y / n）
 VerifyDelete = str.lower（raw_input（>））
如果VerifyDelete ==y：
 FILE = open（ToDo.filename，a +）＃打开文件，整个文件被删除）
 FileLines = FILE.readlines（）＃读取并显示行
在FileLines中的行：
 FILE.truncate（）
如果行[0： 1]！= DeleteItem：＃如果当前行的数字（第一个字符）不等于要删除的数字，则重新写入该行
 FILE.write（line）
 else：
 printNothing Deleted
  

这是一个典型的文件可能看起来像

1。 info here
2.更多的东西在这里
3.更多的东西在这里


print（你想要删除哪个项目？）
DeleteItem = raw_input（ >）＃选择行号删除
print（您确定要删除数字+ DeleteItem +（y / n））
DeleteItem = int（DeleteItem）
VerifyDelete = str.lower（raw_input（>））
如果VerifyDelete ==y：
FILE = open（'data.txt'，r）＃打开文件（尝试w +以及整个文件被删除）
lines = [x.strip（）for x in FILE if int（x [：x.index（'。'）]！= DeleteItem] #read all除了与要删除的行号相匹配的行之外的第一行
FILE.close（）
FILE = open（'data.txt'，w）＃再次打开文件
（x +'\ n'）＃将数据写入文件

else：
print（Nothing Deleted）
DeleteToDo（）

I have a file where each line starts with a number. The user can delete a row by typing in the number of the row the user would like to delete.

The issue I'm having is setting the mode for opening it. When I use a+, the original content is still there. However, tacked onto the end of the file are the lines that I want to keep. On the other hand, when I use w+, the entire file is deleted. I'm sure there is a better way than opening it with w+ mode, deleting everything, and then re-opening it and appending the lines.

 def DeleteToDo(self):
    print "Which Item Do You Want To Delete?"
    DeleteItem = raw_input(">") #select a line number to delete
    print "Are You Sure You Want To Delete Number" + DeleteItem + "(y/n)"
    VerifyDelete = str.lower(raw_input(">"))
    if VerifyDelete == "y":
        FILE = open(ToDo.filename,"a+") #open the file (tried w+ as well, entire file is deleted)
        FileLines = FILE.readlines() #read and display the lines
        for line in FileLines:
            FILE.truncate()
            if line[0:1] != DeleteItem: #if the number (first character) of the current line doesn't equal the number to be deleted, re-write that line
                FILE.write(line)
    else:
        print "Nothing Deleted"

This is what a typical file may look like

1. info here
2. more stuff here
3. even more stuff here

解决方案

def DeleteToDo():
    print ("Which Item Do You Want To Delete?")
    DeleteItem = raw_input(">") #select a line number to delete
    print ("Are You Sure You Want To Delete Number" + DeleteItem + "(y/n)")
    DeleteItem=int(DeleteItem)
    VerifyDelete = str.lower(raw_input(">"))
    if VerifyDelete == "y":
        FILE = open('data.txt',"r") #open the file (tried w+ as well, entire file is deleted)
        lines=[x.strip() for x in FILE if int(x[:x.index('.')])!=DeleteItem] #read all the lines first except the line which matches the line number to be deleted
        FILE.close()
        FILE = open('data.txt',"w")#open the file again
        for x in lines:FILE.write(x+'\n')    #write the data to the file

    else:
        print ("Nothing Deleted")
DeleteToDo()

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