how do i append the items into the list given the keyboard input? (pygame)

Question

I want to get keyboard input of 5 numbers and add them to a list and print the list. my code just prints an empty list without letting the user type in anything. how do i append the items into the list given the keyboard input?

def get_pygame_events():
  pygame_events = pygame.event.get()
  return pygame_events

counter_list = []
key = get_pygame_events()
for num in range(0,5):
    for event in key:
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_1:
                counter_list.append(1)
            if event.key == pygame.K_2:
                counter_list.append(2)
            if event.key == pygame.K_3:
                counter_list.append(3)
            if event.key == pygame.K_4:
                counter_list.append(4)
            if event.key == pygame.K_5:
                counter_list.append(5)
            if  event.key == pygame.K_6:
                counter_list.append(6)
            if event.key == pygame.K_7:
                counter_list.append(7)
            if event.key == pygame.K_8:
                counter_list.append(8)
            if event.key == pygame.K_9:
                counter_list.append(9)
            if event.key == pygame.K_0:
                counter_list.append(0)
print(counter_list)

you should rather run `pygame.event.get()` inside `for`-loop. because it may run very fast and it may get less then 5 keys. This code runs much much faster then people can press keys. And you should rather use `while len(counter_list) < 5:` — furas, Mar 15 '22 at 23:42

furas · Answer 1 · 2022-03-15T23:55:08.073

event.get() doesn't wait for user keypresses (it is not input()) and code run much, much faster then user can press even single key - and this is why you may get empty list. You should run event.get() inside for-loop.

Because sometimes user may press wrong key so better use while len(counter_list) < 5: instead of for num in range(5):

I didn't test this code:

counter_list = []

while len(counter_list) < 5:
    
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_1:
                counter_list.append(1)
            if event.key == pygame.K_2:
                counter_list.append(2)
            if event.key == pygame.K_3:
                counter_list.append(3)
            if event.key == pygame.K_4:
                counter_list.append(4)
            if event.key == pygame.K_5:
                counter_list.append(5)
            if  event.key == pygame.K_6:
                counter_list.append(6)
            if event.key == pygame.K_7:
                counter_list.append(7)
            if event.key == pygame.K_8:
                counter_list.append(8)
            if event.key == pygame.K_9:
                counter_list.append(9)
            if event.key == pygame.K_0:
                counter_list.append(0)

print(counter_list)

This code my have other problem - if you will type keys with big delay then it will block rest of code for long time and it will not update other elements screen - so it will looks like it freeze.

It may need different organization

# -- at the beginning of program

counter_list = []

# --- main loop ---
    
while True:

    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_1:
                counter_list.append(1)
            if event.key == pygame.K_2:
                counter_list.append(2)
            if event.key == pygame.K_3:
                counter_list.append(3)
            if event.key == pygame.K_4:
                counter_list.append(4)
            if event.key == pygame.K_5:
                counter_list.append(5)
            if  event.key == pygame.K_6:
                counter_list.append(6)
            if event.key == pygame.K_7:
                counter_list.append(7)
            if event.key == pygame.K_8:
                counter_list.append(8)
            if event.key == pygame.K_9:
                counter_list.append(9)
            if event.key == pygame.K_0:
                counter_list.append(0)
       
    if len(counter_list) == 5:
        print(counter_list)

    # ... update objects ...

    # ... draw objecte ...

    # ... flip surfaces ...

I mean, we don't really know what this code has to do besides getting 5 numeric values and (seemingly) crashing! I'll add a solution for infinite lists of 5 too! — Fabio Craig Wimmer Florey, Mar 16 '22 at 00:26
@FabioCraigWimmerFlorey good idea - when question ask beginner then it is good to go one step ahead and predict the next question and next problem :) — furas, Mar 16 '22 at 00:33

Fabio Craig Wimmer Florey · Answer 2 · 2022-03-16T00:32:52.633

I just installed pygame and printed pygame.K_1 it turns out to be 49 which happens to be the ASCII for 1.

This means that you can actually do this in a very short manner as such:

if event.type == pygame.KEYDOWN and event.key in range(48,58):
     counter_list.append(int(chr(event.key)))

or you can write a list comprehension as such:

counter_list += [int(chr(event.key)) for event in get_pygame_events() if event.type == pygame.KEYDOWN and event.key in range(48,58)]

This does all the work you are trying to do. As @furas said, the game goes much faster than your inputs, if you want to print all the inputs you can do something like this:

def get_pygame_events():
  pygame_events = pygame.event.get()
  return pygame_events

counter_list = []
while len(counter_list)<5:  
    counter_list += [int(chr(event.key)) for event in get_pygame_events() if event.type == pygame.KEYDOWN and event.key in range(48,58)]
    print(counter_list)

This does everything and it's fairly short, I would add a simple if counter_list before the print statement to avoid the annoying printing of empty counter_list or similar counter_list and remove the pygame_events assignment, that isn't useful at all:

def get_pygame_events():
  return  pygame.event.get()

old_counter_list = []
counter_list = []
SIZE = 5
while len(counter_list)<SIZE:  
    counter_list += [int(chr(event.key)) for event in get_pygame_events() if event.type == pygame.KEYDOWN and event.key in range(48,58)]

    if old_counter_list != counter_list and len(counter_list)!=SIZE:
    # This avoids printing your list infinite times if it isn't the size we want our list to be
        print(counter_list)
        old_counter_list = counter_list[:]

If you want infinite lists of 5 numbers, you can write something like this:

def get_pygame_events():
  return  pygame.event.get()

old_counter_list = []
counter_list = []
SIZE = 5
while True:  
    
    counter_list += [int(chr(event.key)) for event in get_pygame_events() if event.type == pygame.KEYDOWN and event.key in range(48,58)]
    
    if old_counter_list != counter_list:
        # This avoids printing your list infinite times if it isn't the size we want our list to be
        old_counter_list = counter_list[:]
        
    if len(counter_list)==SIZE:
        # This prints the list of 5 elements and resets the list
        print(counter_list)
        counter_list = []

how do i append the items into the list given the keyboard input? (pygame)

2 Answers2