Question

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

Answer 1

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()