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POMultiple timers in Python (Pygame)
 

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  1. POMultiple timers in Python (Pygame)
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    <p>I'm an amateur programmer. I am trying to write a simple program that will measure the reaction time for a series of visual stimuli (flashes of squares) that will be used for a biology experiment. Here's my code (beware, first time coding a graphical interface):</p> <pre><code>stimulus = pygame.Rect(100,250,100,100) #draw on surface object time.sleep(2) #wait for 2 seconds before it appears screen.fill(BLACK) pygame.draw.rect(screen,WHITE,stimulus) pygame.display.update(stimulus) #record time stimulus appeared t0 = time.clock() #clear screen ("flash" illusion) time.sleep(0.5) #***PROBLEM*** screen.fill(BLACK) pygame.display.update(stimulus) while True: for event in pygame.event.get(): if event.type == KEYDOWN: t1 = time.clock() print t1-t0 if event.type == QUIT: pygame.quit() sys.exit() </code></pre> <p>The program was working fine before I included the block with the line marked "problem". The reaction time printed seemed reasonable. However, I want the square to disappear after a while, as though it just "flashed". After including the time.sleep(0.5), the time printed is no longer correct. It is always 0.5xxxx or greater, no matter how fast I press. Is there any workaround?</p> <p>P.S. I need it to disappear because I want to present a sequence of flashes with predetermined (not constant) pauses in between.</p> <p>Thanks.</p> <p><strong>Edit</strong></p> <p>I need to achieve two things: 1. The shape must flash on the screen for 0.5 sec. 2. The program must create a timestamp (e.g. write to a list) every time the spacebar is pressed (even if it is pressed randomly twice between two flashes).</p>
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    1. COThere is no way to have perfect timing accuracy. When you call `time.sleep` the OS puts the process in a suspended state, then when *at least* `0.5` seconds are passed an interrupt will wake the OS which will put your program in running state. If you want almost perfect timings you should use special real-time OSes.
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    2. COCan you post code that is [SSCCE](http://sscce.org/). It would make it easier for people to help you. the names screen, BLACK, WHITE, KEYDOWN have not been imported or defined, so I am unable to run your code.
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      1. POMultiple timers in Python (Pygame)
      1. USMarwan Alsabbagh
    3. CO@Bakuriu Any suggestions for a "real-time OS" that runs Python? Thanks.
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