The program isn't printing what I want ("too slow") after the except with the KeyboardInterrupt, which should end the program and print the string, instead the program just ends. I tried messing around with it a bit but can't seem to figure it out. What should I do?
import os
import signal
import threading
from random import randint
def timed_input(interval, *args):
t = threading.Timer(interval, os.kill, args=(os.getpid(), signal.SIGINT))
t.start()
try:
return int(input(*args))
except:
pass
finally:
t.cancel()
while True:
want = randint(1,9)
try:
got = timed_input(5, f'type "{want}": ')
except KeyboardInterrupt:
print('too slow')
else:
if got != want:
print('You Lose.')
break
This is because your first function is removing the KeyboardInterrupt thus making the second try block useless.
To fix this add another except block for the first function so it is properly raised:
import os
import signal
import threading
from random import randint
def timed_input(interval, *args):
t = threading.Timer(interval, os.kill, args=(os.getpid(), signal.SIGINT))
t.start()
try:
return int(input(*args))
except KeyboardInterrupt:
raise
except ValueError:
pass
finally:
t.cancel()
while True:
want = randint(1,9)
try:
got = timed_input(5, f'type "{want}": ')
except KeyboardInterrupt:
print('too slow')
else:
if got != want:
print('You Lose.')
break
This question already has answers here:
Keyboard input with timeout?
(28 answers)
Closed 3 years ago.
What I would like to be able to do is ask a user a question using input. For example:
print('some scenario')
prompt = input("You have 10 seconds to choose the correct answer...\n")
and then if the time elapses print something like
print('Sorry, times up.')
Any help pointing me in the right direction would be greatly appreciated.
If it is acceptable to block the main thread when user haven't provided an answer:
from threading import Timer
timeout = 10
t = Timer(timeout, print, ['Sorry, times up'])
t.start()
prompt = "You have %d seconds to choose the correct answer...\n" % timeout
answer = input(prompt)
t.cancel()
Otherwise, you could use #Alex Martelli's answer (modified for Python 3) on Windows (not tested):
import msvcrt
import time
class TimeoutExpired(Exception):
pass
def input_with_timeout(prompt, timeout, timer=time.monotonic):
sys.stdout.write(prompt)
sys.stdout.flush()
endtime = timer() + timeout
result = []
while timer() < endtime:
if msvcrt.kbhit():
result.append(msvcrt.getwche()) #XXX can it block on multibyte characters?
if result[-1] == '\r':
return ''.join(result[:-1])
time.sleep(0.04) # just to yield to other processes/threads
raise TimeoutExpired
Usage:
try:
answer = input_with_timeout(prompt, 10)
except TimeoutExpired:
print('Sorry, times up')
else:
print('Got %r' % answer)
On Unix you could try:
import select
import sys
def input_with_timeout(prompt, timeout):
sys.stdout.write(prompt)
sys.stdout.flush()
ready, _, _ = select.select([sys.stdin], [],[], timeout)
if ready:
return sys.stdin.readline().rstrip('\n') # expect stdin to be line-buffered
raise TimeoutExpired
Or:
import signal
def alarm_handler(signum, frame):
raise TimeoutExpired
def input_with_timeout(prompt, timeout):
# set signal handler
signal.signal(signal.SIGALRM, alarm_handler)
signal.alarm(timeout) # produce SIGALRM in `timeout` seconds
try:
return input(prompt)
finally:
signal.alarm(0) # cancel alarm
Interesting problem, this seems to work:
import time
from threading import Thread
answer = None
def check():
time.sleep(2)
if answer != None:
return
print("Too Slow")
Thread(target = check).start()
answer = input("Input something: ")
is there any way for ask question by if statement and after afew sec if user didnot give any answer , if state use a default answer?
inp = input("change music(1) or close the app(2)")
if inp = '1':
print("Music changed)
elif inp = '2':
print("good by")
in this case if user dont give any answer after 30 sec by default if statement choose number 3
from threading import Timer
out_of_time = False
def time_ran_out():
print ('You didn\'t answer in time') # Default answer
out_of_time = True
seconds = 5 # waiting time in seconds
t = Timer(seconds,time_ran_out)
t.start()
inp = input("change music(1) or close the app(2):\n")
if inp != None and not out_of_time:
if inp == '1':
print("Music changed")
elif inp == '2':
print("good by")
else:
print ("Wrong input")
t.cancel()
Timer Objects
This class represents an action that should be run only after a certain amount of time has passed — a timer. Timer is a
subclass of Thread and as such also functions as an example of
creating custom threads.
Timers are started, as with threads, by calling their start() method.
The timer can be stopped (before its action has begun) by calling the
cancel() method. The interval the timer will wait before executing its
action may not be exactly the same as the interval specified by the
user.
For example:
def hello():
print("hello, world")
t = Timer(30.0, hello)
t.start() # after 30 seconds, "hello, world" will be printed
class threading.Timer(interval, function, args=None, kwargs=None)
Create a timer that will run function with arguments args and keyword
arguments kwargs, after interval seconds have passed. If args is None
(the default) then an empty list will be used. If kwargs is None (the
default) then an empty dict will be used.
cancel()
Stop the timer, and cancel the execution of the timer’s action. This will only work if the timer is still in its waiting
stage.
Here's an alternative way to do it (python 3), using multiprocessing. Note, to get the stdin to work in the child process, you have to re open it first. I'm also converting the input from string to int to use with the multiprocessing value, so you might want to error check there as well.
import multiprocessing as mp
import time
import sys
import os
TIMEOUT = 10
DEFAULT = 3
def get_input(resp: mp.Value, fn):
sys.stdin = os.fdopen(fn)
v = input('change music(1) or close the app (2)')
try:
resp.value = int(v)
except ValueError:
pass # bad input, maybe print error message, try again in loop.
# could also use another mp.Value to signal main to restart the timer
if __name__ == '__main__':
now = time.time()
end = now + TIMEOUT
inp = 0
resp = mp.Value('i', 0)
fn = sys.stdin.fileno()
p = mp.Process(name='Get Input', target=get_input, args=(resp, fn))
p.start()
while True:
t = end - time.time()
print('Checking for timeout: Time = {:.2f}, Resp = {}'.format(t, resp.value))
if t <= 0:
print('Timeout occurred')
p.terminate()
inp = DEFAULT
break
elif resp.value > 0:
print('Response received:', resp.value)
inp = resp.value
break
else:
time.sleep(1)
print()
if inp == 1:
print('Music Changed')
elif inp == 2:
print('Good Bye')
else:
print('Other value:', inp)
I've made this little alarm clock with a little help from my brother. I tried it last night, with out the nonBlockingRawInput and that worked fine, but with the nonBlockingRawInput it didn't work. Today I've tried it but neither of them work! I will post the code with the nonBlockingRawInput and the "non" file. If you want the code without nonBlockingRawInput, just ask.
Thanks in advance.
alarm rpi.py:
import time
import os
from non import nonBlockingRawInput
name = input("Enter your name.")
print("Hello, " + name)
alarm_HH = input("Enter the hour you want to wake up at")
alarm_MM = input("Enter the minute you want to wake up at")
print("You want to wake up at " + alarm_HH + ":" + alarm_MM)
while True:
now = time.localtime()
if now.tm_hour == int(alarm_HH) and now.tm_min == int(alarm_MM):
print("ALARM NOW!")
os.popen("open mpg321 /home/pi/voltage.mp3")
break
else:
print("no alarm")
timeout = 60 - now.tm_sec
if nonBlockingRawInput('', timeout) == 'stop':
break
non.py:
import signal
class AlarmException(Exception):
pass
def alarmHandler(signum, frame):
raise AlarmException
def nonBlockingRawInput(prompt='', timeout=20):
signal.signal(signal.SIGALRM, alarmHandler)
signal.alarm(timeout)
try:
text = input(prompt)
signal.alarm(0)
return text
except AlarmException:
pass
signal.signal(signal.SIGALRM, signal.SIG_IGN)
return ''
I've been looking at your code for a while now. As far as I can understand you want to be able to run an alarm while also being able to type "stop" in the shell to end the program, to this end you can make the alarm a thread. The thread will check if its time to say "ALARM!" and open the mp3. If the user hasn't typed stop in the shell, the thread will sleep and check again later.
I essentially used your code and just put it into an alarm thread class:
import time
import os
import threading
class Alarm(threading.Thread):
def __init__(self, hours, minutes):
super(Alarm, self).__init__()
self.hours = int(hours)
self.minutes = int(minutes)
self.keep_running = True
def run(self):
try:
while self.keep_running:
now = time.localtime()
if (now.tm_hour == self.hours and now.tm_min == self.minutes):
print("ALARM NOW!")
os.popen("voltage.mp3")
return
time.sleep(60)
except:
return
def just_die(self):
self.keep_running = False
name = raw_input("Enter your name: ")
print("Hello, " + name)
alarm_HH = input("Enter the hour you want to wake up at: ")
alarm_MM = input("Enter the minute you want to wake up at: ")
print("You want to wake up at: {0:02}:{1:02}").format(alarm_HH, alarm_MM)
alarm = Alarm(alarm_HH, alarm_MM)
alarm.start()
try:
while True:
text = str(raw_input())
if text == "stop":
alarm.just_die()
break
except:
print("Yikes lets get out of here")
alarm.just_die()
It is worth noting, that when the thread is sleeping, with:
time.sleep(60)
And you typed stop in the shell the thread would have to wake up before it realised it was dead, so you could at worst end up waiting a minute for the program to close!
import winsound,time
a= int(input("Enter how many times I have beep :"))
b= int(input("Enter when to wake up (in seconds) :"))
time.sleep(b)
for i in range(a):
winsound.Beep(3000,100)
winsound.Beep(2500,100)
winsound.Beep(2000,100)
winsound.Beep(1000,100)
winsound.Beep(500,100)
I am reading serial data and writing to a csv file using a while loop. I want the user to be able to kill the while loop once they feel they have collected enough data.
while True:
#do a bunch of serial stuff
#if the user presses the 'esc' or 'return' key:
break
I have done something like this using opencv, but it doesn't seem to be working in this application (and i really don't want to import opencv just for this function anyway)...
# Listen for ESC or ENTER key
c = cv.WaitKey(7) % 0x100
if c == 27 or c == 10:
break
So. How can I let the user break out of the loop?
Also, I don't want to use keyboard interrupt, because the script needs to continue to run after the while loop is terminated.
The easiest way is to just interrupt it with the usual Ctrl-C (SIGINT).
try:
while True:
do_something()
except KeyboardInterrupt:
pass
Since Ctrl-C causes KeyboardInterrupt to be raised, just catch it outside the loop and ignore it.
There is a solution that requires no non-standard modules and is 100% transportable:
import _thread
def input_thread(a_list):
raw_input() # use input() in Python3
a_list.append(True)
def do_stuff():
a_list = []
_thread.start_new_thread(input_thread, (a_list,))
while not a_list:
stuff()
the following code works for me. It requires openCV (import cv2).
The code is composed of an infinite loop that is continuously looking for a key pressed. In this case, when the 'q' key is pressed, the program ends. Other keys can be pressed (in this example 'b' or 'k') to perform different actions such as change a variable value or execute a function.
import cv2
while True:
k = cv2.waitKey(1) & 0xFF
# press 'q' to exit
if k == ord('q'):
break
elif k == ord('b'):
# change a variable / do something ...
elif k == ord('k'):
# change a variable / do something ...
For Python 3.7, I copied and changed the very nice answer by user297171 so it works in all scenarios in Python 3.7 that I tested.
import threading as th
keep_going = True
def key_capture_thread():
global keep_going
input()
keep_going = False
def do_stuff():
th.Thread(target=key_capture_thread, args=(), name='key_capture_thread', daemon=True).start()
while keep_going:
print('still going...')
do_stuff()
pip install keyboard
import keyboard
while True:
# do something
if keyboard.is_pressed("q"):
print("q pressed, ending loop")
break
Here is a solution that worked for me. Got some ideas from posts here and elsewhere. Loop won't end until defined key (abortKey) is pressed. The loop stops as fast as possible and does not try to run to next iteration.
from pynput import keyboard
from threading import Thread
from time import sleep
def on_press(key, abortKey='esc'):
try:
k = key.char # single-char keys
except:
k = key.name # other keys
print('pressed %s' % (k))
if k == abortKey:
print('end loop ...')
return False # stop listener
def loop_fun():
while True:
print('sleeping')
sleep(5)
if __name__ == '__main__':
abortKey = 't'
listener = keyboard.Listener(on_press=on_press, abortKey=abortKey)
listener.start() # start to listen on a separate thread
# start thread with loop
Thread(target=loop_fun, args=(), name='loop_fun', daemon=True).start()
listener.join() # wait for abortKey
pyHook might help. http://sourceforge.net/apps/mediawiki/pyhook/index.php?title=PyHook_Tutorial#tocpyHook%5FTutorial4
See keyboard hooks; this is more generalized-- if you want specific keyboard interactions and not just using KeyboardInterrupt.
Also, in general (depending on your use) I think having the Ctrl-C option still available to kill your script makes sense.
See also previous question: Detect in python which keys are pressed
There is always sys.exit().
The system library in Python's core library has an exit function which is super handy when prototyping.
The code would be along the lines of:
import sys
while True:
selection = raw_input("U: Create User\nQ: Quit")
if selection is "Q" or selection is "q":
print("Quitting")
sys.exit()
if selection is "U" or selection is "u":
print("User")
#do_something()
I modified the answer from rayzinnz to end the script with a specific key, in this case the escape key
import threading as th
import time
import keyboard
keep_going = True
def key_capture_thread():
global keep_going
a = keyboard.read_key()
if a== "esc":
keep_going = False
def do_stuff():
th.Thread(target=key_capture_thread, args=(), name='key_capture_thread', daemon=True).start()
i=0
while keep_going:
print('still going...')
time.sleep(1)
i=i+1
print (i)
print ("Schleife beendet")
do_stuff()
This is the solution I found with threads and standard libraries
Loop keeps going on until one key is pressed
Returns the key pressed as a single character string
Works in Python 2.7 and 3
import thread
import sys
def getch():
import termios
import sys, tty
def _getch():
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(fd)
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
return _getch()
def input_thread(char):
char.append(getch())
def do_stuff():
char = []
thread.start_new_thread(input_thread, (char,))
i = 0
while not char :
i += 1
print "i = " + str(i) + " char : " + str(char[0])
do_stuff()
From following this thread down the rabbit hole, I came to this, works on Win10 and Ubuntu 20.04. I wanted more than just killing the script, and to use specific keys, and it had to work in both MS and Linux..
import _thread
import time
import sys
import os
class _Getch:
"""Gets a single character from standard input. Does not echo to the screen."""
def __init__(self):
try:
self.impl = _GetchWindows()
except ImportError:
self.impl = _GetchUnix()
def __call__(self): return self.impl()
class _GetchUnix:
def __init__(self):
import tty, sys
def __call__(self):
import sys, tty, termios
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(sys.stdin.fileno())
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
class _GetchWindows:
def __init__(self):
import msvcrt
def __call__(self):
import msvcrt
msvcrt_char = msvcrt.getch()
return msvcrt_char.decode("utf-8")
def input_thread(key_press_list):
char = 'x'
while char != 'q': #dont keep doing this after trying to quit, or 'stty sane' wont work
time.sleep(0.05)
getch = _Getch()
char = getch.impl()
pprint("getch: "+ str(char))
key_press_list.append(char)
def quitScript():
pprint("QUITTING...")
time.sleep(0.2) #wait for the thread to die
os.system('stty sane')
sys.exit()
def pprint(string_to_print): #terminal is in raw mode so we need to append \r\n
print(string_to_print, end="\r\n")
def main():
key_press_list = []
_thread.start_new_thread(input_thread, (key_press_list,))
while True:
#do your things here
pprint("tick")
time.sleep(0.5)
if key_press_list == ['q']:
key_press_list.clear()
quitScript()
elif key_press_list == ['j']:
key_press_list.clear()
pprint("knock knock..")
elif key_press_list:
key_press_list.clear()
main()
This may be helpful
install pynput with --
pip install pynput
from pynput.keyboard import Key, Listener
def on_release(key):
if key == Key.esc:
# Stop listener
return False
# Collect events until released
while True:
with Listener(
on_release=on_release) as listener:
listener.join()
break
Here is a simple Windows solution that safely ends current iteration and then quits. I used it with a counter example that breaks the loop with 'Esc' key and quits. It uses kbhit() and getch() functions from msvcrt package. Time package is only called for easement reasons (to set time delay between events).
import msvcrt, time
print("Press 'Esc' to stop the loop...")
x = 0
while True:
x += 1
time.sleep(0.5)
print(x)
if msvcrt.kbhit():
if msvcrt.getch() == b'\x1b':
print("You have pressed Esc! See you!")
time.sleep(2)
break
kbhit() function returns True if a keypress is waiting to be read
getch() function reads a keypress and returns the resulting character as a byte string. It can be used with any key
b'\x1b' is the byte string character for the 'Esc' key.
Here another example using threading.Event, without the need for catching SIGINT (Ctrl+c).
As #Atcold has mentioned in a comment below the accepted answer, pressing Ctrl+c in the loop, may interrupt a long running operation and leave it in an undefined state. This can specially annoying, when that long running operation comes from a library that you are calling.
In the example below, the user needs to press q and then press Enter. If you want to capture the key stroke immediately, you need something like _Getch() from this answer.
import time
from threading import Thread, Event
def read_input(q_entered_event):
c = input()
if c == "q":
print("User entered q")
q_entered_event.set()
def do_long_running_stuff():
q_pressed_event = Event()
input_thread = Thread(target=read_input,
daemon=True,
args=(q_pressed_event,))
input_thread.start()
while True:
print("I am working ...")
time.sleep(1)
if q_pressed_event.is_set():
break
print("Process stopped by user.")
if __name__ == "__main__":
do_long_running_stuff()
from time import sleep
from threading import Thread
import threading
stop_flag = 0
def Wait_Char():
global stop_flag
v = input("Enter Char")
if(v == "z"):
stop_flag = 1
def h():
while(True):
print("Hello Feto")
time.sleep(1)
if(stop_flag == 1):
break
thread1 = Thread(target=Wait_Char)
thread2 = Thread(target=h)
thread1.start()
thread2.start()
print("threads finished...exiting")
This isn't the best way but it can do the job you want,
Running 2 Threads one waiting for the Key you want to stop the loop with
(Wait_Char Method)
and one for loop
(H Method)
And both see a global variable stop_flag which control the stoping process
Stop when I press z
from pynput import keyboard
def on_press(key):
if key == keyboard.Key.esc:
return False
i = 0
with keyboard.Listener(on_press=on_press) as listener:
# Your infinite loop
while listener.running:
print(i)
i=i+1
print("Done")
It works ...
import keyboard
while True:
print('please say yes')
if keyboard.is_pressed('y'):
break
print('i got u :) ')
print('i was trying to write you are a idiot ')
print(' :( ')
for enter use 'ENTER'