Efficient way of adding one character at a time from one string to another in Python

I'm currently making a function using pygame that draws a message on the screen, adding one character each frame (i.e. The Hunt for Red October). I know that I could simply copy (or pass) gradually bigger slices from the original string, but I know that it would be very resource-intensive. Is there a better way to do this?

Code, using gradually bigger slices:

def full_screen_dialog_tt(thesurface, thefont, theclock, message, thebeep):
 i = 0
 while(i < len(message)): # Initialize the string display
  theclock.tick(60)
  thesurface.fill((0, 0, 0))
  thesurface.blit(thefont.render(message[i]+"_"))
  pygame.display.flip()
  thebeep.play()
 while(1): # Whole string is here now
  theclock.开发者_运维百科tick(60)
  for event in pygame.events.get():
   if event.type == MOUSEBUTTONDOWN: return

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In a place where you are intentionally slowing down the game (for the text fade-in) - does it really matter? You could pass the whole string, and change the display routine to display one more letter in every frame.

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Can't you just print the characters one at a time displaced without clearing the background? You can get the character using slicing.

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Assuming you're having a screen object available, this might work:

import time
text = 'The Hunt for Red October'
myfont = pygame.font.SysFont("arial", 16)
for index, ch in enumerate(text): 
    letter = myfont.render(ch, True, (0, 0, 0), (255, 255, 255))
    screen.blit(letter, (index * 20, 20))
    time.sleep(1)

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You can access a single character from a string using indexes:

>>> s = 'string'
>>> s[2]
'r'