What I want is to be able to run a function every second, irrelevant of how long the function takes (it should always be under a second). I've considered a number of options but not sure which is best.
If I just use the delay function it isn't going to take into account the time the function takes to run.
If I time the function and then subtract that from a second and make up the rest in the delay it's not going to take into account the time calculations.
I tried using threading.timer (I'm not sure about the ins and outs of how this works) but it did seem to be slower than the 1s.
Here's the code I tried for testing threading.timer:
def update(i):
sys.stdout.write(str(i)+'\r')
sys.stdout.flush()
print i
i += 1
threading.Timer(1, update, [i]).start()
Is there a way to do this irrelevant of the length of the time the function takes?
This will do it, and its accuracy won't drift with time.
import time
start_time = time.time()
interval = 1
for i in range(20):
time.sleep(start_time + i*interval - time.time())
f()
The approach using a threading.Timer (see code below) should in fact not be used, as a new thread is launched at every interval and this loop can never be stopped cleanly.
# as seen here: https://stackoverflow.com/a/3393759/1025391
def update(i):
threading.Timer(1, update, [i+1]).start()
# business logic here
If you want a background loop it is better to launch a new thread that runs a loop as described in the other answer. Which is able to receive a stop signal, s.t. you can join() the thread eventually.
This related answer seems to be a great starting point to implement this.
if f() always takes less than a second then to run it on a one second boundary (without a drift):
import time
while True:
time.sleep(1 - time.monotonic() % 1)
f()
The idea is from #Dave Rove's answer to a similar question.
To understand how it works, consider an example:
time.monotonic() returns 13.7 and time.sleep(0.3) is called
f() is called around (±some error) 14 seconds (since time.monotonic() epoch)
f() is run and it takes 0.1 (< 1) seconds
time.monotonic() returns around 14.1 seconds and time.sleep(0.9) is called
Step 2. is repeated around 15 seconds (since time.monotonic() epoch)
f() is run and it takes 0.3 (< 1) seconds (note: the value is different from Step 2.)
time.monotonic() returns around 15.3 and time.sleep(0.7) is called
f() is called around 16 seconds and the loop is repeated.
At each step f() is called on a one second boundary (according to time.monotonic() timer). The errors do not accumulate. There is no drift.
See also: How to run a function periodically in python (using tkinter).
How about this: After each run, sleep for (1.0 - launch interval) seconds. You can change the terminate condition by changing while True:. Although if the your function takes more than 1 second to run, this will go wrong.
from time import time, sleep
while True:
startTime = time()
yourFunction()
endTime = time()-startTime
sleep(1.0-endTime)
Threading may be a good choice. The basic concept is as follows.
import threading
def looper():
# i as interval in seconds
threading.Timer(i, looper).start()
# put your action here
foo()
#to start
looper()
I would like to recommend the following code. You can replace the True with any condition if you want.
while True:
time.sleep(1) #sleep for 1 second
func() #function you want to trigger
Tell me if it works.
Related
I would like to let a while loop run, the stuff thats happening inside takes about 2 seconds to complete (it varies a small amount), so if I use time.sleep(60 or 58) it would still shift slightly. So what I would like to do is that the while loop starts for example at 16:00:00 (because I click run) and does its stuff, waits and then starts again at 16:01:00, so a minute later and so on. How can I do that?
Measure the time taken by the operation. Then subtract that from your loop period to get the amount of time to sleep.
import time
while True:
start = time.time()
# do your thing
time.sleep(60 - (time.time() - start))
Where are you putting time.sleep() in your code? Have you tried putting it at the end of the while loop when all of the processing is complete?
Calling the stop function will stop your while loop for the amount you pass. This works I tested it
def stop(t):
running = False
time.sleep(t)
running = True
while running:
# Do something
I'm making a client/server program and on the client I want a clock on the GUI that displays the running time. Now there's plenty of tutorials on here on how to make a clock/timer and I think I have that part down.
The issue is making one that runs in the background while the rest of the code executes. At the moment I have a loop for my timer that the code doesn't move past, so it just starts counting the timer then doesn't do anything else after that. At least until the timer is stopped anyway.
I'm guessing I need to find a way to make it run in the background, but I don't know how and I can't find the answer. It has been suggested to me that I should use threading/multithreading, but that looks kinda complicated and I can't quite figure it out.
Is there a better way to do it or is threading the way to go?
You can keep track of time passed since a certain point by subtracting the start time from the current time. You can then update the timer value with this (if you have a lot of other code running in between this will become slower so you might want to round it).
import time
start = time.time()
while doing_stuff:
do_stuff()
GUI.update_timer(time.time() - start)
I don't see any reason why threading is not a good idea. For one, if you have complex computations to run in your code, threading will enhance the performance by running your code and the timer in the background in tandem. Here's something that may help illustrate my point with a simple function to square numbers:
import time
import threading
def square():
start_time = time.time()
x = int(input('Enter number: '))
squared = x*x
print('Square is: %s ' %squared)
print('Time elapsed: %s seconds' %(time.time() - start_time))
set_thread = threading.Thread(target=square) #set Thread() to run on square() function
set_thread.start()
#Output:
Enter number: 5
Square is: 25
Time elapsed: 1.4820027351379395 seconds
Of course, the simple function above may take only a few seconds. The timer begins when the function is called and stops when the code in the square() block has run. But imagine a situation where your code has much more complex computations such as insert multiple values into a database or sort a large list of data and write to a file at the same time.
I'm writing a countdown clock in python, but it looks like the time module only goes down to the second. Is there a way for me to accurately determine when exactly 1 second has passed?
Seems like my question was a little confusing, let me clarify. I need to run some code, then, at the end, the program enters a while loop and exits once at least 1000 milliseconds have passed since the time the code started running
If you know the code you want to run will take less than 1 second, then 1 - elapsed time will give you the remaining time to sleep, no while loop required.
now = time.time()
foo()
time.sleep(1 - (time.time() - now))
There will be some overhead with the arithmetic, but it's within 1/100 of a second and will be strictly greater than 1 second, as you request. I ran the following code:
import time
import random
def foo():
time.sleep(random.random())
now = time.time()
foo()
time.sleep(1 - (time.time() - now))
print "Time elapsed: {}".format(time.time() - now)
Output:
Time elapsed: 1.00379300117
You can run this several times to verify it gives the output you want, no matter how long foo takes.
Unless it takes longer than 1 second, then the sleep time will be negative which will result in IOError. You would need to check for that case.
Or, if you need to kill the function if 1 second has passed, check this question
Here is a way which will work, though im not sure which modules you are limited to.
import time
def procedure:
time.sleep(2.5)
# measure wall time
t0 = time.time()
procedure()
print time.time() - t0, "seconds wall time"
2.50023603439 seconds wall time
where procedure is a reference to the function you are timing.
By default the time module gives you the time to the 10^-5 second
import time
time.time()
>>> 1480643510.89443
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
What is the best way to repeatedly execute a function every x seconds in Python?
Hi so here is the code I have:
client = myclient(info1,info2)
sellor()
Contractor()
It works perfectly but what I would like to do is to make python launch that code every 60 seconds indefinitely...
I don't actually understand how I have to put the code together with the time loop
Any help is appreciated
Thank's
If the 60 seconds ignores the time it takes to execute your code):
from time import sleep
while True:
sleep(60)
# your code here
but if the 60 seconds takes into account the time it takes to execute your code:
from time import sleep
from os import fork
while True:
sleep(60)
fork() # create child process
# your code here
Use the sleep method. Just create a loop (while, for, whatever) and sleep for 60 secs every iteration.
import time
while True:
client = myclient(info1,info2)
sellor()
Contractor()
time.sleep(10)
hope it works,all the best mate
import time
repeat_time = 3.0
while True:
start_time = time.time()
# Your code goes here
time.sleep(max(repeat_time - (time.time() - start_time), 0.0))
And your code will be executed exactly every "repeat_time"
You could use sleep as already mentioned. But because there may be a variable amount of time needed for your own functions to run, this wouldn't necessarily mean your functions are run every 60 seconds.
If it was important that the period between each start of your functions is closer to 60 seconds, you could use time. I haven't tried this but something like
import time
while True:
# Get the current time
startTime = time.time()
# Your functions
client = myclient(info1,info2)
sellor()
Contractor()
delay = True
while delay:
if time.time() - startTime > 60:
delay = False # Break the delay
You might also think of just scheduling the task through windows scheduler. The benefit here would end the script once run and then execute the script again after scheduled interval. In the second approach it seems that the script instance process would continually run and only use the sleep function to do nothing for the specified time. I take it this way if the scripts fails at any instance you might have to keep a check to restart the script. While as a scheduled activity the script will be executed in any case at that specified intervals.
You might also not want the process thread to be kept running for the python script executed. I will research on this and you might get to hear form our other folks in the mean while.
Regards,
Harshal
import time
word = {"success":0, "desire":0, "effort":0, ...}
def cleaner(x):
dust = ",./<>?;''[]{}\=+_)(*&^%$##!`~"
for letter in x:
if letter in dust:
x = x[0:x.index(letter)]+x[x.index(letter)+1:]
else:
pass
return x #alhamdlillah it worked 31.07.12
print "input text to analyze"
itext = cleaner(raw_input()).split()
t = time.clock()
for iword in itext:
if iword in word:
word[iword] += 1
else:
pass
print t
print len(itext)
every time i call the code, t will increase. can anyone explain the underlying concept/reason behind this. perhaps in terms of system process? thank you very much, programming lads.
Because you're printing out the current time each time you run the script
That's how time works, it advances, constantly.
If you want to measure the time taken for your for loop (between the first call to time.clock() and the end), print out the difference in times:
print time.clock() - t
You are printing the current time... of course it increases every time you run the code.
From the python documentation for time.clock():
On Unix, return the current processor time as a floating point number
expressed in seconds. The precision, and in fact the very definition
of the meaning of “processor time”, depends on that of the C function
of the same name, but in any case, this is the function to use for
benchmarking Python or timing algorithms.
On Windows, this function returns wall-clock seconds elapsed since the
first call to this function, as a floating point number, based on the
Win32 function QueryPerformanceCounter(). The resolution is typically
better than one microsecond.
time.clock() returns the elapsed CPU time since the process was created. CPU time is based on how many cycles the CPU spent in the context of the process. It is a monotonic function during the lifetime of a process, i.e. if you call time.clock() several times in the same execution, you will get a list of increasing numbers. The difference between two successive invocations of clock() could be less than the elasped wall-clock time or more, depending on wheather the CPU was not running at 100% (e.g. there was some waiting for I/O) or if you have a multithreaded program which consumes more than 100% of CPU time (e.g. multicore CPU with 2 threads using 75% each -> you'd get 150% of the wall-clock time). But if you call clock() once in one process, then rerun the program again, you might get lower value than the one before, if it takes less time to process the input in the new process.
What you should be doing instead is to use time.time() which returns the current Unix timestamp with fractional (subsecond) precision. You should call it once before the processing is started and once after that and subtract the two values in order to compute the wall-clock time elapsed between the two invocations.
Note that on Windows time.clock() returns the elapsed wall-clock time since the process was started. It is like calling time.time() immediately at the beginning of the script and then subtracting the value from later calls to time.time().
There is a really good library called jackedCodeTimerPy that works better than the time module. It also has some clever error checking so you may want to try it out.
Using jackedCodeTimerPy your code should look like this:
# import time
from jackedCodeTimerPY import JackedTiming
JTimer = JackedTiming()
word = {"success":0, "desire":0, "effort":0}
def cleaner(x):
dust = ",./<>?;''[]{}\=+_)(*&^%$##!`~"
for letter in x:
if letter in dust:
x = x[0:x.index(letter)]+x[x.index(letter)+1:]
else:
pass
return x #alhamdlillah it worked 31.07.12
print "input text to analyze"
itext = cleaner(raw_input()).split()
# t = time.clock()
JTimer.start('timer_1')
for iword in itext:
if iword in word:
word[iword] += 1
else:
pass
# print t
JTimer.stop('timer_1')
print JTimer.report()
print len(itext)
It gives really good reports like
label min max mean total run count
------- ----------- ----------- ----------- ----------- -----------
imports 0.00283813 0.00283813 0.00283813 0.00283813 1
loop 5.96046e-06 1.50204e-05 6.71864e-06 0.000335932 50
I like how it gives you statistics on it and the number of times the timer is run.
It's simple to use. If i want to measure the time code takes in a for loop i just do the following:
from jackedCodeTimerPY import JackedTiming
JTimer = JackedTiming()
for i in range(50):
JTimer.start('loop') # 'loop' is the name of the timer
doSomethingHere = 'This is really useful!'
JTimer.stop('loop')
print(JTimer.report()) # prints the timing report
You can can also have multiple timers running at the same time.
JTimer.start('first timer')
JTimer.start('second timer')
do_something = 'amazing'
JTimer.stop('first timer')
do_something = 'else'
JTimer.stop('second timer')
print(JTimer.report()) # prints the timing report
There are more use example in the repo. Hope this helps.
https://github.com/BebeSparkelSparkel/jackedCodeTimerPY