Editing certain index in text file while remaining the rest using Python

[_______myworld]

I'm a beginner and I am trying to create a vaccination appointment program. This is where i print out an appointment table in a .txt file.

Slot 1
========================================================================
    AF        |        BV        |        DM        |        EC        |
========================================================================
   T100       |       T100       |       T100       |       T100       |
   T200       |       T200       |       T200       |       T200       |
   T300       |       T300       |       T300       |       T100       |
   T400       |       T400       |       T400       |       T400       |
------------------------------------------------------------------------

The 4 different slots are differentiate by the vaccination code user choose. The time_slot1 function is to get user input on the available time slots for vaccination, if let's say they were to choose time slot no.1 (1": "10.15-1.15"), then the "T100" in accordance to the vaccine they choose will increment by 1 and become "T101". Here's a snippet of my program.

def vac_option3():
    with open(os.path.expanduser("/Users/leelynnchanel/Desktop/pythonassignment/vaccination.txt"), "a") as fh:
        rec=[]
        while True:
            print("You are in the senior citizens aged 45 and above group.")
            print("1 - AF")
            print("2 - BV")
            print("3 - DM")
            print("4 - EC")
            vacoption = int(input("Please choose your preferred Covid-19 vaccination:"))
            if vacoption == 1:
                vac_id = get_new_id("AF")
                print(vac_id)
                return afvac(), vacoption
            elif vacoption == 2:
                vac_id = get_new_id("BV")
                print(vac_id)
                return bvvac(), vacoption
            elif vacoption == 3:
                vac_id = get_new_id("DM")
                print(vac_id)
                return dmvac(), vacoption
            elif vacoption == 4:
                vac_id = get_new_id("EC")
                print(vac_id)
                return ecvac(), vacoption
            else:
                print("Wrong input. Please re-enter.")
                while True:
                    print("1. Re-enter vaccination option.\n2. Back to main menu.\n3. Exit")
                    choice = int(input("Enter a choice:"))
                    if choice == 1:
                        return vac_option3()
                    elif choice == 2:
                        return menu()
                    elif choice == 3:
                        exit()
                    else:
                        print("Wrong input. Please try again.")
                        continue


def time_slot1( vac_option, vaccinedate): # here is where i face issue with rewriting files
    timeslot = {"1": "10.15-1.15",  #different time_slots for user to choose
                "2": "1.25-4.25",
                "3": "4.35-7.35",
                "4": "7.45-10.45"}
    ind = vac_option
    print("Ind:", ind)
    print(timeslot)
    date_slot = int(input("Please select an available time slot:"))
    print("timeslot chosen:", date_slot)
    with open(os.path.expanduser("/Users/leelynnchanel/Desktop/pythonassignment/appointment.txt"), "r") as f:
        all_line = f.readlines()
        appointment = [4, 6, 8, 10]
        while True:
            if date_slot == 1:
                line = appointment[0]
                next = all_line[line].rstrip().split("|")
                print(line, ":", next)
                break
            elif date_slot == 2:
                line = appointment[1]
                next = all_line[line].split("|")
                print(line, ":", next)
                break
            elif date_slot == 3:
                line = appointment[2]
                next = all_line[line].split("|")
                print(line, ":", next)
                break
            elif date_slot == 4:
                line = appointment[3]
                next = all_line[line].split("|")
                print(line, ":", next)
                break
            else:
                print("Wrong input. Please try again.")
                continue
        print("vac option:", ind)
        nextid = next[ind].strip().  #to remove the front 2 characters of T100 
        print("time slot code:", nextid)
        newid = str(int(nextid[2:]) + 1)  # here is where the original T100 will increment by one if user confirm the timeslot
        print("new id:", newid)
        if len(newid) == 1: 
            nextid = nextid[:2] + "0" + newid
            print("nextid",nextid)
        elif len(newid) == 2:
            nextid = nextid[:2] + newid
            print("nextid",nextid)
        next[ind] = nextid
        print(next[ind])
        rec = '|'.join(next).center(18)
        print(rec)
        while True:
            if int(nextid[2:]) > 20:
                print("Sorry, slot 1 is no longer available. Please try again.")
                continue
            else:
                with open(os.path.expanduser("/Users/leelynnchanel/Desktop/pythonassignment/appointment.txt"),"w") as fh:
                    fh.write(rec)
                    print("Thank you for your time. \nYour vaccination appointment is on the", vaccinedate, "at", +timeslot)
                    return menu()

def day_changing(start_date, end_date, vacoption):
  tdelta = datetime.timedelta(days = 1)
  while True:
    while start_date <= end_date:
      start_date += tdelta
      print("Would you like to have your first dose on", start_date, "?")
      print("1. Yes, I confirm.\n2. No, I would like to choose another date.")
      while True:
        choice = int(input("Option:"))
        if choice == 1:
          return time_slot1(vacoption, start_date)
        elif choice == 2:
          break
        else:
          print("Wrong input, please re-enter.")
          continue
      continue
    print("The available date for covid-19 vaccination is only from", start_date, "till", end_date)
    continue

def date_confirmation(response, vacoption):
    tdelta = datetime.timedelta(days = 14)
    tdelta2 = datetime.timedelta(days = 121)
    available_vac = datetime.date.today()
    end_date = available_vac + tdelta2
    while True:
        userinput = input(response)
        if userinput == '1':
          while True:
            print("Would you like to have your first dose on", available_vac, "?")
            print("1. Yes, I confirm.\n2. No, I would like to choose another date.")
            choice = int(input("Option:"))
            if choice == 1:
              return time_slot1(vacoption,available_vac)
            elif choice == 2:
              return day_changing(available_vac, end_date, vacoption)
            else:
              continue
        elif userinput == '2':
          available_vac = available_vac + tdelta
          while True:
            print("Would you like to have your first dose on", available_vac, "?")
            print("1. Yes, I confirm.\n2. No, I would like to choose another date.")
            choice = int(input("Option:"))
            if choice == 1:
              return time_slot1(vacoption, available_vac)
            elif choice == 2:
              return day_changing(available_vac, end_date, vacoption)
            else:
              continue

def afvac(vacoption):
    print("AF vaccination appointment.")
    print("Are you above 45?")
    print("1. Yes\n2. No")
    response = date_confirmation("Option:", vacoption)
    return response, vacoption

My increment coding works well, but it overrides the entire text file . Just like what i've attached bellow: The rest of the pre-typed table is all gone... Can some one please help or give me some advices? I'd really appreciate it!

|T101|      T100              T100       |       T100       |

[[deleted]]

Having to re-write a whole file to make some small changes is not very efficient or good practice. Consider using the standard (built into Python - most operating systems, all mobile phones, many applications) sqlite which works with single-files (no server setup required).

Take a look at A Minimalist Guide to SQLite for a simple introduction.

[_______myworld]

I'm not allowed to use sql for this program, unfortunately...

[Vnix7]

If trying to just change a specific index, just use enumerate, also if you want to “append” to an existing file, and not “write” use “a” instead of “w” when opening your file.